Another visualization of quicksort. Here, each row corresponds to the state of the array prior to recursing into each partition. The red lines represent the pivots.
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February 9, 2016 01:54
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Quicksort II
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| license: gpl-3.0 |
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| body { | |
| padding: 10px 0; | |
| } | |
| svg { | |
| float: left; | |
| } | |
| .line { | |
| stroke: #000; | |
| stroke-linecap: round; | |
| } | |
| .line--pivot { | |
| stroke: #f00; | |
| stroke-width: 3px; | |
| } | |
| .line--inactive { | |
| stroke: #ddd; | |
| } | |
| </style> | |
| <body> | |
| <script src="//d3js.org/d3.v3.min.js"></script> | |
| <script> | |
| var n = 200, | |
| array = d3.shuffle(d3.range(n)), | |
| levels = quicksort(array); | |
| var margin = {top: 2, right: 20, bottom: 2, left: 20}, | |
| width = 960 - margin.left - margin.right, | |
| height = 30 - margin.top - margin.bottom; | |
| var x = d3.scale.ordinal() | |
| .domain(d3.range(n)) | |
| .rangePoints([0, width]); | |
| var a = d3.scale.linear() | |
| .domain([0, n - 1]) | |
| .range([-45, 45]); | |
| var svg = d3.select("body").selectAll("svg") | |
| .data(levels) | |
| .enter().append("svg") | |
| .attr("width", width + margin.left + margin.right) | |
| .attr("height", height + margin.top + margin.bottom) | |
| .append("g") | |
| .attr("transform", "translate(" + margin.left + "," + margin.top + ")"); | |
| svg.append("g") | |
| .attr("class", "line") | |
| .selectAll("line") | |
| .data(function(d) { return d; }) | |
| .enter().append("line") | |
| .attr("transform", function(d, i) { return "translate(" + x(i) + "," + height + ")rotate(" + a(d == null ? i : d) + ")"; }) | |
| .attr("class", function(d, i) { return d == null ? "line--inactive" : i in this.parentNode.__data__.pivots ? "line--pivot" : null; }) | |
| .attr("y2", -height); | |
| function quicksort(array) { | |
| var levels = []; | |
| function partition(left, right, pivot) { | |
| var v = array[pivot]; | |
| swap(pivot, --right); | |
| for (var i = left; i < right; ++i) if (array[i] <= v) swap(i, left++); | |
| swap(left, right); | |
| return left; | |
| } | |
| function swap(i, j) { | |
| var t = array[i]; | |
| array[i] = array[j]; | |
| array[j] = t; | |
| } | |
| function recurse(left, right, depth) { | |
| var pivot = (left + right) >> 1; | |
| if (!levels[depth]) levels[depth] = new Array(array.length), levels[depth].pivots = {}; | |
| for (var i = left; i < right; ++i) levels[depth][i] = array[i]; | |
| levels[depth].pivots[pivot] = 1; | |
| pivot = partition(left, right, pivot); | |
| if (left < pivot - 1) recurse(left, pivot, depth + 1); | |
| if (pivot + 1 < right - 1) recurse(pivot + 1, right, depth + 1); | |
| } | |
| if (array.length > 1) recurse(0, array.length, 0); | |
| return levels; | |
| } | |
| d3.select(self.frameElement).style("height", (height + margin.top + margin.bottom) * levels.length + 20 + "px"); | |
| </script> |
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