rust version: old method comparable to method in main

flamegraph.svg

@@ -1,414 +0,0 @@
-<?xml version="1.0" standalone="no"?><!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd"><svg version="1.1" width="1200" height="470" onload="init(evt)" viewBox="0 0 1200 470" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:fg="http://github.com/jonhoo/inferno"><!--Flame graph stack visualization. See https://github.com/brendangregg/FlameGraph for latest version, and http://www.brendangregg.com/flamegraphs.html for examples.--><!--NOTES: --><defs><linearGradient id="background" y1="0" y2="1" x1="0" x2="0"><stop stop-color="#eeeeee" offset="5%"/><stop stop-color="#eeeeb0" offset="95%"/></linearGradient></defs><style type="text/css">
-text { font-family:"Verdana"; font-size:12px; fill:rgb(0,0,0); }
-#title { text-anchor:middle; font-size:17px; }
-#search { opacity:0.1; cursor:pointer; }
-#search:hover, #search.show { opacity:1; }
-#subtitle { text-anchor:middle; font-color:rgb(160,160,160); }
-#unzoom { cursor:pointer; }
-#frames > *:hover { stroke:black; stroke-width:0.5; cursor:pointer; }
-.hide { display:none; }
-.parent { opacity:0.5; }
-</style><script type="text/ecmascript"><![CDATA[
-        var nametype = 'Function:';
-        var fontsize = 12;
-        var fontwidth = 0.59;
-        var xpad = 10;
-        var inverted = false;
-        var searchcolor = 'rgb(230,0,230)';
-        var fluiddrawing = true;
-        var truncate_text_right = false;
-    ]]><![CDATA["use strict";
-var details, searchbtn, unzoombtn, matchedtxt, svg, searching, frames;
-function init(evt) {
-    details = document.getElementById("details").firstChild;
-    searchbtn = document.getElementById("search");
-    unzoombtn = document.getElementById("unzoom");
-    matchedtxt = document.getElementById("matched");
-    svg = document.getElementsByTagName("svg")[0];
-    frames = document.getElementById("frames");
-    total_samples = parseInt(frames.attributes.total_samples.value);
-    searching = 0;
-
-    // Use GET parameters to restore a flamegraph's state.
-    var restore_state = function() {
-        var params = get_params();
-        if (params.x && params.y)
-            zoom(find_group(document.querySelector('[*|x="' + params.x + '"][y="' + params.y + '"]')));
-        if (params.s)
-            search(params.s);
-    };
-
-    if (fluiddrawing) {
-        // Make width dynamic so the SVG fits its parent's width.
-        svg.removeAttribute("width");
-        // Edge requires us to have a viewBox that gets updated with size changes.
-        var isEdge = /Edge\/\d./i.test(navigator.userAgent);
-        var update_for_width_change = function() {
-            if (isEdge) {
-                svg.attributes.viewBox.value = "0 0 " + svg.width.baseVal.value + " " + svg.height.baseVal.value;
-            }
-
-            // Keep consistent padding on left and right of frames container.
-            frames.attributes.width.value = svg.width.baseVal.value - xpad * 2;
-
-            // Text truncation needs to be adjusted for the current width.
-            var el = frames.children;
-            for(var i = 0; i < el.length; i++) {
-                update_text(el[i]);
-            }
-
-            // Keep search elements at a fixed distance from right edge.
-            var svgWidth = svg.width.baseVal.value;
-            searchbtn.attributes.x.value = svgWidth - xpad - 100;
-            matchedtxt.attributes.x.value = svgWidth - xpad - 100;
-        };
-        window.addEventListener('resize', function() {
-            update_for_width_change();
-        });
-        // This needs to be done asynchronously for Safari to work.
-        setTimeout(function() {
-            unzoom();
-            update_for_width_change();
-            restore_state();
-            if (!isEdge) {
-                svg.removeAttribute("viewBox");
-            }
-        }, 0);
-    } else {
-        restore_state();
-    }
-}
-// event listeners
-window.addEventListener("click", function(e) {
-    var target = find_group(e.target);
-    if (target) {
-        if (target.nodeName == "a") {
-            if (e.ctrlKey === false) return;
-            e.preventDefault();
-        }
-        if (target.classList.contains("parent")) unzoom();
-        zoom(target);
-
-        // set parameters for zoom state
-        var el = target.querySelector("rect");
-        if (el && el.attributes && el.attributes.y && el.attributes["fg:x"]) {
-            var params = get_params()
-            params.x = el.attributes["fg:x"].value;
-            params.y = el.attributes.y.value;
-            history.replaceState(null, null, parse_params(params));
-        }
-    }
-    else if (e.target.id == "unzoom") {
-        unzoom();
-
-        // remove zoom state
-        var params = get_params();
-        if (params.x) delete params.x;
-        if (params.y) delete params.y;
-        history.replaceState(null, null, parse_params(params));
-    }
-    else if (e.target.id == "search") search_prompt();
-}, false)
-// mouse-over for info
-// show
-window.addEventListener("mouseover", function(e) {
-    var target = find_group(e.target);
-    if (target) details.nodeValue = nametype + " " + g_to_text(target);
-}, false)
-// clear
-window.addEventListener("mouseout", function(e) {
-    var target = find_group(e.target);
-    if (target) details.nodeValue = ' ';
-}, false)
-// ctrl-F for search
-window.addEventListener("keydown",function (e) {
-    if (e.keyCode === 114 || (e.ctrlKey && e.keyCode === 70)) {
-        e.preventDefault();
-        search_prompt();
-    }
-}, false)
-// functions
-function get_params() {
-    var params = {};
-    var paramsarr = window.location.search.substr(1).split('&');
-    for (var i = 0; i < paramsarr.length; ++i) {
-        var tmp = paramsarr[i].split("=");
-        if (!tmp[0] || !tmp[1]) continue;
-        params[tmp[0]]  = decodeURIComponent(tmp[1]);
-    }
-    return params;
-}
-function parse_params(params) {
-    var uri = "?";
-    for (var key in params) {
-        uri += key + '=' + encodeURIComponent(params[key]) + '&';
-    }
-    if (uri.slice(-1) == "&")
-        uri = uri.substring(0, uri.length - 1);
-    if (uri == '?')
-        uri = window.location.href.split('?')[0];
-    return uri;
-}
-function find_child(node, selector) {
-    var children = node.querySelectorAll(selector);
-    if (children.length) return children[0];
-    return;
-}
-function find_group(node) {
-    var parent = node.parentElement;
-    if (!parent) return;
-    if (parent.id == "frames") return node;
-    return find_group(parent);
-}
-function orig_save(e, attr, val) {
-    if (e.attributes["fg:orig_" + attr] != undefined) return;
-    if (e.attributes[attr] == undefined) return;
-    if (val == undefined) val = e.attributes[attr].value;
-    e.setAttribute("fg:orig_" + attr, val);
-}
-function orig_load(e, attr) {
-    if (e.attributes["fg:orig_"+attr] == undefined) return;
-    e.attributes[attr].value = e.attributes["fg:orig_" + attr].value;
-    e.removeAttribute("fg:orig_" + attr);
-}
-function g_to_text(e) {
-    var text = find_child(e, "title").firstChild.nodeValue;
-    return (text)
-}
-function g_to_func(e) {
-    var func = g_to_text(e);
-    // if there's any manipulation we want to do to the function
-    // name before it's searched, do it here before returning.
-    return (func);
-}
-function update_text(e) {
-    var r = find_child(e, "rect");
-    var t = find_child(e, "text");
-    var w = parseFloat(r.attributes.width.value) * frames.attributes.width.value / 100 - 3;
-    var txt = find_child(e, "title").textContent.replace(/\([^(]*\)$/,"");
-    t.attributes.x.value = format_percent((parseFloat(r.attributes.x.value) + (100 * 3 / frames.attributes.width.value)));
-    // Smaller than this size won't fit anything
-    if (w < 2 * fontsize * fontwidth) {
-        t.textContent = "";
-        return;
-    }
-    t.textContent = txt;
-    // Fit in full text width
-    if (/^ *\$/.test(txt) || t.getComputedTextLength() < w)
-        return;
-    if (truncate_text_right) {
-        // Truncate the right side of the text.
-        for (var x = txt.length - 2; x > 0; x--) {
-            if (t.getSubStringLength(0, x + 2) <= w) {
-                t.textContent = txt.substring(0, x) + "..";
-                return;
-            }
-        }
-    } else {
-        // Truncate the left side of the text.
-        for (var x = 2; x < txt.length; x++) {
-            if (t.getSubStringLength(x - 2, txt.length) <= w) {
-                t.textContent = ".." + txt.substring(x, txt.length);
-                return;
-            }
-        }
-    }
-    t.textContent = "";
-}
-// zoom
-function zoom_reset(e) {
-    if (e.tagName == "rect") {
-        e.attributes.x.value = format_percent(100 * parseInt(e.attributes["fg:x"].value) / total_samples);
-        e.attributes.width.value = format_percent(100 * parseInt(e.attributes["fg:w"].value) / total_samples);
-    }
-    if (e.childNodes == undefined) return;
-    for(var i = 0, c = e.childNodes; i < c.length; i++) {
-        zoom_reset(c[i]);
-    }
-}
-function zoom_child(e, x, zoomed_width_samples) {
-    if (e.tagName == "text") {
-        var parent_x = parseFloat(find_child(e.parentNode, "rect[x]").attributes.x.value);
-        e.attributes.x.value = format_percent(parent_x + (100 * 3 / frames.attributes.width.value));
-    } else if (e.tagName == "rect") {
-        e.attributes.x.value = format_percent(100 * (parseInt(e.attributes["fg:x"].value) - x) / zoomed_width_samples);
-        e.attributes.width.value = format_percent(100 * parseInt(e.attributes["fg:w"].value) / zoomed_width_samples);
-    }
-    if (e.childNodes == undefined) return;
-    for(var i = 0, c = e.childNodes; i < c.length; i++) {
-        zoom_child(c[i], x, zoomed_width_samples);
-    }
-}
-function zoom_parent(e) {
-    if (e.attributes) {
-        if (e.attributes.x != undefined) {
-            e.attributes.x.value = "0.0%";
-        }
-        if (e.attributes.width != undefined) {
-            e.attributes.width.value = "100.0%";
-        }
-    }
-    if (e.childNodes == undefined) return;
-    for(var i = 0, c = e.childNodes; i < c.length; i++) {
-        zoom_parent(c[i]);
-    }
-}
-function zoom(node) {
-    var attr = find_child(node, "rect").attributes;
-    var width = parseInt(attr["fg:w"].value);
-    var xmin = parseInt(attr["fg:x"].value);
-    var xmax = xmin + width;
-    var ymin = parseFloat(attr.y.value);
-    unzoombtn.classList.remove("hide");
-    var el = frames.children;
-    for (var i = 0; i < el.length; i++) {
-        var e = el[i];
-        var a = find_child(e, "rect").attributes;
-        var ex = parseInt(a["fg:x"].value);
-        var ew = parseInt(a["fg:w"].value);
-        // Is it an ancestor
-        if (!inverted) {
-            var upstack = parseFloat(a.y.value) > ymin;
-        } else {
-            var upstack = parseFloat(a.y.value) < ymin;
-        }
-        if (upstack) {
-            // Direct ancestor
-            if (ex <= xmin && (ex+ew) >= xmax) {
-                e.classList.add("parent");
-                zoom_parent(e);
-                update_text(e);
-            }
-            // not in current path
-            else
-                e.classList.add("hide");
-        }
-        // Children maybe
-        else {
-            // no common path
-            if (ex < xmin || ex >= xmax) {
-                e.classList.add("hide");
-            }
-            else {
-                zoom_child(e, xmin, width);
-                update_text(e);
-            }
-        }
-    }
-}
-function unzoom() {
-    unzoombtn.classList.add("hide");
-    var el = frames.children;
-    for(var i = 0; i < el.length; i++) {
-        el[i].classList.remove("parent");
-        el[i].classList.remove("hide");
-        zoom_reset(el[i]);
-        update_text(el[i]);
-    }
-}
-// search
-function reset_search() {
-    var el = document.querySelectorAll("#frames rect");
-    for (var i = 0; i < el.length; i++) {
-        orig_load(el[i], "fill")
-    }
-    var params = get_params();
-    delete params.s;
-    history.replaceState(null, null, parse_params(params));
-}
-function search_prompt() {
-    if (!searching) {
-        var term = prompt("Enter a search term (regexp " +
-            "allowed, eg: ^ext4_)", "");
-        if (term != null) {
-            search(term)
-        }
-    } else {
-        reset_search();
-        searching = 0;
-        searchbtn.classList.remove("show");
-        searchbtn.firstChild.nodeValue = "Search"
-        matchedtxt.classList.add("hide");
-        matchedtxt.firstChild.nodeValue = ""
-    }
-}
-function search(term) {
-    var re = new RegExp(term);
-    var el = frames.children;
-    var matches = new Object();
-    var maxwidth = 0;
-    for (var i = 0; i < el.length; i++) {
-        var e = el[i];
-        // Skip over frames which are either not visible, or below the zoomed-to frame
-        if (e.classList.contains("hide") || e.classList.contains("parent")) {
-            continue;
-        }
-        var func = g_to_func(e);
-        var rect = find_child(e, "rect");
-        if (func == null || rect == null)
-            continue;
-        // Save max width. Only works as we have a root frame
-        var w = parseInt(rect.attributes["fg:w"].value);
-        if (w > maxwidth)
-            maxwidth = w;
-        if (func.match(re)) {
-            // highlight
-            var x = parseInt(rect.attributes["fg:x"].value);
-            orig_save(rect, "fill");
-            rect.attributes.fill.value = searchcolor;
-            // remember matches
-            if (matches[x] == undefined) {
-                matches[x] = w;
-            } else {
-                if (w > matches[x]) {
-                    // overwrite with parent
-                    matches[x] = w;
-                }
-            }
-            searching = 1;
-        }
-    }
-    if (!searching)
-        return;
-    var params = get_params();
-    params.s = term;
-    history.replaceState(null, null, parse_params(params));
-
-    searchbtn.classList.add("show");
-    searchbtn.firstChild.nodeValue = "Reset Search";
-    // calculate percent matched, excluding vertical overlap
-    var count = 0;
-    var lastx = -1;
-    var lastw = 0;
-    var keys = Array();
-    for (k in matches) {
-        if (matches.hasOwnProperty(k))
-            keys.push(k);
-    }
-    // sort the matched frames by their x location
-    // ascending, then width descending
-    keys.sort(function(a, b){
-        return a - b;
-    });
-    // Step through frames saving only the biggest bottom-up frames
-    // thanks to the sort order. This relies on the tree property
-    // where children are always smaller than their parents.
-    for (var k in keys) {
-        var x = parseInt(keys[k]);
-        var w = matches[keys[k]];
-        if (x >= lastx + lastw) {
-            count += w;
-            lastx = x;
-            lastw = w;
-        }
-    }
-    // display matched percent
-    matchedtxt.classList.remove("hide");
-    var pct = 100 * count / maxwidth;
-    if (pct != 100) pct = pct.toFixed(1);
-    matchedtxt.firstChild.nodeValue = "Matched: " + pct + "%";
-}
-function format_percent(n) {
-    return n.toFixed(4) + "%";
-}
-]]></script><rect x="0" y="0" width="100%" height="470" fill="url(#background)"/><text id="title" x="50.0000%" y="24.00">Flame Graph</text><text id="details" x="10" y="453.00"> </text><text id="unzoom" class="hide" x="10" y="24.00">Reset Zoom</text><text id="search" x="1090" y="24.00">Search</text><text id="matched" x="1090" y="453.00"> </text><svg id="frames" x="10" width="1180" total_samples="4176"><g><title>[unknown] (1 samples, 0.02%)</title><rect x="0.0000%" y="373" width="0.0239%" height="15" fill="rgb(227,0,7)" fg:x="0" fg:w="1"/><text x="0.2500%" y="383.50"></text></g><g><title>[unknown] (1 samples, 0.02%)</title><rect x="0.0000%" y="357" width="0.0239%" height="15" fill="rgb(217,0,24)" fg:x="0" fg:w="1"/><text x="0.2500%" y="367.50"></text></g><g><title>[unknown] (1 samples, 0.02%)</title><rect x="0.0000%" y="341" width="0.0239%" height="15" fill="rgb(221,193,54)" fg:x="0" fg:w="1"/><text x="0.2500%" y="351.50"></text></g><g><title>[unknown] (1 samples, 0.02%)</title><rect x="0.0000%" y="325" width="0.0239%" height="15" fill="rgb(248,212,6)" fg:x="0" fg:w="1"/><text x="0.2500%" y="335.50"></text></g><g><title>[unknown] (1 samples, 0.02%)</title><rect x="0.0000%" y="309" width="0.0239%" height="15" fill="rgb(208,68,35)" fg:x="0" fg:w="1"/><text x="0.2500%" y="319.50"></text></g><g><title>[unknown] (1 samples, 0.02%)</title><rect x="0.0000%" y="293" width="0.0239%" height="15" fill="rgb(232,128,0)" fg:x="0" fg:w="1"/><text x="0.2500%" y="303.50"></text></g><g><title>[unknown] (1 samples, 0.02%)</title><rect x="0.0000%" y="277" width="0.0239%" height="15" fill="rgb(207,160,47)" fg:x="0" fg:w="1"/><text x="0.2500%" y="287.50"></text></g><g><title>[unknown] (1 samples, 0.02%)</title><rect x="0.0000%" y="261" width="0.0239%" height="15" fill="rgb(228,23,34)" fg:x="0" fg:w="1"/><text x="0.2500%" y="271.50"></text></g><g><title>[unknown] (3 samples, 0.07%)</title><rect x="0.0239%" y="357" width="0.0718%" height="15" fill="rgb(218,30,26)" fg:x="1" fg:w="3"/><text x="0.2739%" y="367.50"></text></g><g><title>[unknown] (3 samples, 0.07%)</title><rect x="0.0239%" y="341" width="0.0718%" height="15" fill="rgb(220,122,19)" fg:x="1" fg:w="3"/><text x="0.2739%" y="351.50"></text></g><g><title>[unknown] (3 samples, 0.07%)</title><rect x="0.0239%" y="325" width="0.0718%" height="15" fill="rgb(250,228,42)" fg:x="1" fg:w="3"/><text x="0.2739%" y="335.50"></text></g><g><title>[unknown] (3 samples, 0.07%)</title><rect x="0.0239%" y="309" width="0.0718%" height="15" fill="rgb(240,193,28)" fg:x="1" fg:w="3"/><text x="0.2739%" y="319.50"></text></g><g><title>[unknown] (3 samples, 0.07%)</title><rect x="0.0239%" y="293" width="0.0718%" height="15" fill="rgb(216,20,37)" fg:x="1" fg:w="3"/><text x="0.2739%" y="303.50"></text></g><g><title>[unknown] (3 samples, 0.07%)</title><rect x="0.0239%" y="277" width="0.0718%" height="15" fill="rgb(206,188,39)" fg:x="1" fg:w="3"/><text x="0.2739%" y="287.50"></text></g><g><title>[unknown] (3 samples, 0.07%)</title><rect x="0.0239%" y="261" width="0.0718%" height="15" fill="rgb(217,207,13)" fg:x="1" fg:w="3"/><text x="0.2739%" y="271.50"></text></g><g><title>[unknown] (2 samples, 0.05%)</title><rect x="0.0479%" y="245" width="0.0479%" height="15" fill="rgb(231,73,38)" fg:x="2" fg:w="2"/><text x="0.2979%" y="255.50"></text></g><g><title>[unknown] (2 samples, 0.05%)</title><rect x="0.0479%" y="229" width="0.0479%" height="15" fill="rgb(225,20,46)" fg:x="2" fg:w="2"/><text x="0.2979%" y="239.50"></text></g><g><title>[unknown] (2 samples, 0.05%)</title><rect x="0.0479%" y="213" width="0.0479%" height="15" fill="rgb(210,31,41)" fg:x="2" fg:w="2"/><text x="0.2979%" y="223.50"></text></g><g><title>[unknown] (1 samples, 0.02%)</title><rect x="0.0718%" y="197" width="0.0239%" height="15" fill="rgb(221,200,47)" fg:x="3" fg:w="1"/><text x="0.3218%" y="207.50"></text></g><g><title>[unknown] (2 samples, 0.05%)</title><rect x="13.6734%" y="261" width="0.0479%" height="15" fill="rgb(226,26,5)" fg:x="571" fg:w="2"/><text x="13.9234%" y="271.50"></text></g><g><title>[unknown] (1 samples, 0.02%)</title><rect x="13.6973%" y="245" width="0.0239%" height="15" fill="rgb(249,33,26)" fg:x="572" fg:w="1"/><text x="13.9473%" y="255.50"></text></g><g><title>[unknown] (1 samples, 0.02%)</title><rect x="13.6973%" y="229" width="0.0239%" height="15" fill="rgb(235,183,28)" fg:x="572" fg:w="1"/><text x="13.9473%" y="239.50"></text></g><g><title>[unknown] (1 samples, 0.02%)</title><rect x="13.6973%" y="213" width="0.0239%" height="15" fill="rgb(221,5,38)" fg:x="572" fg:w="1"/><text x="13.9473%" y="223.50"></text></g><g><title>[unknown] (1 samples, 0.02%)</title><rect x="13.6973%" y="197" width="0.0239%" height="15" fill="rgb(247,18,42)" fg:x="572" fg:w="1"/><text x="13.9473%" y="207.50"></text></g><g><title>[unknown] (1 samples, 0.02%)</title><rect x="13.6973%" y="181" width="0.0239%" height="15" fill="rgb(241,131,45)" fg:x="572" fg:w="1"/><text x="13.9473%" y="191.50"></text></g><g><title>[unknown] (1 samples, 0.02%)</tLine truncated

src/main.rs

@@ -6,8 +6,7 @@ const NUM_FIELDS: usize = SIZE * SIZE;
 
 struct SField {
     field: Vec<u8>,
-    skipf: Vec<u8>,
+    fixed: Vec<bool>,
-    skipb: Vec<u8>,
     pos: usize,
     possible_values: Vec<Vec<u8>>,
 }
@@ -27,50 +26,18 @@ impl SField {
             0,0,8,2,0,0,0,6,0,
         ];
 
-        fn find_fixed_streak_forward(mut idx: usize, field: &[u8]) -> u8 {
+        let mut fixed = Vec::with_capacity(SIZE * SIZE);
-            let mut fixed_count = 1;
+        field.iter().for_each(|e| {
-            idx += 1;
+            if *e == 0 {
-
+                fixed.push(false);
-            while idx < NUM_FIELDS && field[idx] > 0 {
+            } else {
-                fixed_count += 1;
+                fixed.push(true);
-                idx += 1;
-            }
-
-            fixed_count
-        }
-
-        fn find_fixed_streak_backward(mut idx: usize, field: &[u8]) -> u8 {
-            let mut fixed_count = 1;
-            idx -= 1;
-
-            while idx < NUM_FIELDS && field[idx] > 0 {
-                fixed_count += 1;
-                idx -= 1;
-            }
-
-            fixed_count
-        }
-
-        let mut skipf = vec![0; NUM_FIELDS + 1];
-        for (idx, nr) in field.iter().enumerate() {
-            match nr {
-                0 => skipf[idx] = *nr,
-                _ => skipf[idx] = find_fixed_streak_forward(idx, &field),
-            }
-        }
-
-        let mut skipb = vec![0; NUM_FIELDS + 1];
-        for (idx, nr) in field.iter().enumerate().rev() {
-            match nr {
-                0 => skipb[idx + 1] = *nr,
-                _ => skipb[idx + 1] = find_fixed_streak_backward(idx, &field),
-            }
             }
+        });
 
         SField {
             field,
-            skipf,
+            fixed,
-            skipb,
             pos: 0,
             possible_values: vec![vec![]; SIZE * SIZE],
         }
@@ -78,7 +45,7 @@ impl SField {
 
     fn build_possible_values_db(&mut self) {
         for idx in 0..NUM_FIELDS {
-            if self.field[idx] != 0 {
+            if self.fixed[idx] {
                 continue;
             }
             self.pos = idx;
@@ -96,51 +63,71 @@ impl SField {
 
     pub fn solve_backtracking(&mut self) -> bool {
         let mut num_solutions = 0;
-
         loop {
-            if !self.put_valid_nr() {
+            if self.is_end() {
-                self.clear_current_field();
-                if !self.prev() {
-                    self.print_clear();
-                    self.print();
-                    println!("Number of solutions: {}", num_solutions);
-                    break;
-                }
-                continue;
-            }
-
-            if !self.next() {
                 num_solutions += 1;
+
                 if num_solutions % 10_000 == 0 {
                     self.print_clear();
                     self.print();
                     println!("Number of solutions: {}", num_solutions);
                 }
 
+                if self.is_fixed() {
+                    continue;
+                }
                 self.clear_current_field();
                 self.prev();
+                self.goto_prev_free_field();
+            }
+
+            if self.is_fixed() {
+                self.next();
+                continue;
+            }
+
+            if self.goto_next_free_field() {
+                if self.put_valid_nr() {
+                    self.next();
+                    continue;
+                } else {
+                    self.clear_current_field();
+                    if !self.prev() {
+                        println!("Number of solutions: {}", num_solutions);
+                        break;
+                    }
+                    if !self.goto_prev_free_field() {
+                        println!("Number of solutions: {}", num_solutions);
+                        break;
+                    }
+                }
             }
         }
 
         num_solutions > 0
     }
 
+    #[inline(always)]
     fn print_gray(&self) {
         print!("\x1b\x5b\x31\x3b\x33\x30\x6d");
     }
 
+    #[inline(always)]
     fn print_green(&self) {
         print!("\x1b\x5b\x31\x3b\x33\x32\x6d");
     }
 
+    #[inline(always)]
     fn print_neutral(&self) {
         print!("\x1b\x5b\x31\x3b\x30\x6d");
     }
 
+    #[inline(always)]
     fn print_clear(&self) {
         print!("\x1b\x5b\x48\x1b\x5b\x32\x4a");
     }
 
+    #[inline(always)]
     fn print(&self) {
         for i in 0..NUM_FIELDS {
             if i != 0 && i % SIZE == 0 {
@@ -162,10 +149,50 @@ impl SField {
         println!();
     }
 
+    #[inline(always)]
     fn clear_current_field(&mut self) {
         self.set(0);
     }
 
+    #[inline(always)]
+    fn goto_prev_free_field(&mut self) -> bool {
+        while {
+            if !self.is_fixed() {
+                return true;
+            }
+            self.prev()
+        } {}
+
+        false
+    }
+
+    #[inline(always)]
+    fn goto_next_free_field(&mut self) -> bool {
+        while {
+            if !self.is_fixed() {
+                return true;
+            }
+            self.next()
+        } {}
+
+        false
+    }
+
+    #[inline(always)]
+    fn _put_valid_nr(&mut self) -> bool {
+        let current_nr = self.get_field_at_pos(self.pos);
+
+        for nr in current_nr..(SIZE + 1) as u8 {
+            if self.ok(nr) {
+                self.set(nr);
+                return true;
+            }
+        }
+
+        false
+    }
+
+    #[inline(always)]
     fn put_valid_nr(&mut self) -> bool {
         let current_nr = self.get_field_at_pos(self.pos);
 
@@ -187,10 +214,32 @@ impl SField {
         false
     }
 
+    #[inline(always)]
+    fn is_end(&self) -> bool {
+        !self.field.contains(&0)
+    }
+
+    #[inline(always)]
     fn ok(&self, nr: u8) -> bool {
         self.block_ok(nr) && self.row_ok(nr) && self.col_ok(nr)
     }
 
+    #[inline(always)]
+    fn _pos_to_xy(&self) -> (usize, usize) {
+        let y = self.pos / SIZE;
+        let x = self.pos % SIZE;
+        (x + 1, y + 1)
+    }
+
+    #[inline(always)]
+    fn is_fixed(&self) -> bool {
+        // safety: self.pos can be used to index the field unchecked
+        //         since the only methods modifying self.pos are
+        //         `next()` and `prev()` and they do bounds checking
+        unsafe { *self.fixed.get_unchecked(self.pos) }
+    }
+
+    #[inline(always)]
     fn get_field_at_pos(&self, pos: usize) -> u8 {
         // safety:
         //     TODO
@@ -199,22 +248,26 @@ impl SField {
         unsafe { *self.field.get_unchecked(pos) }
     }
 
+    #[inline(always)]
     fn set(&mut self, nr: u8) {
         self.field[self.pos] = nr;
     }
 
+    #[inline(always)]
     fn get_row(&self, row: &mut [u8; SIZE]) {
         for (idx, row_elem) in row.iter_mut().enumerate() {
             *row_elem = self.get_field_at_pos((self.pos / SIZE) * SIZE + idx);
         }
     }
 
+    #[inline(always)]
     fn get_col(&self, col: &mut [u8; SIZE]) {
         for (idx, col_elem) in col.iter_mut().enumerate() {
             *col_elem = self.get_field_at_pos(idx * SIZE + self.pos % SIZE);
         }
     }
 
+    #[inline(always)]
     fn get_block(&self, block: &mut [u8; SIZE]) {
         let block_start_row = self.pos / SIZE / BLOCK_SIZE * BLOCK_SIZE;
         let block_start_col = self.pos % SIZE / BLOCK_SIZE * BLOCK_SIZE;
@@ -227,46 +280,48 @@ impl SField {
         }
     }
 
+    #[inline(always)]
     fn block_ok(&self, nr: u8) -> bool {
         let mut block = [0; SIZE];
         self.get_block(&mut block);
         !block.contains(&nr)
     }
 
+    #[inline(always)]
     fn row_ok(&self, nr: u8) -> bool {
         let mut row = [0; SIZE];
         self.get_row(&mut row);
         !row.contains(&nr)
     }
 
+    #[inline(always)]
     fn col_ok(&self, nr: u8) -> bool {
         let mut col = [0; SIZE];
         self.get_col(&mut col);
         !col.contains(&nr)
     }
 
+    #[inline(always)]
     fn next(&mut self) -> bool {
-        let new_pos = self.pos + 1 + unsafe { *self.skipf.get_unchecked(self.pos + 1) as usize };
+        if self.pos == NUM_FIELDS - 1 {
-
-        if new_pos >= NUM_FIELDS {
             return false;
         }
 
-        self.pos = new_pos;
+        self.pos += 1;
         true
     }
 
+    #[inline(always)]
     fn prev(&mut self) -> bool {
-        let new_pos = self.pos - 1 - unsafe { *self.skipb.get_unchecked(self.pos) as usize };
+        if self.pos == 0 {
-
-        if new_pos >= NUM_FIELDS {
             return false;
         }
 
-        self.pos = new_pos;
+        self.pos -= 1;
         true
     }
 
+    #[inline(always)]
     fn solve(&mut self) {
         let now = Instant::now();
         if !self.solve_backtracking() {