See also merge sort.
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February 9, 2016 01:02
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Quicksort
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| license: gpl-3.0 |
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| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <body> | |
| <style> | |
| line { | |
| stroke: #000; | |
| stroke-width: 1.5px; | |
| } | |
| </style> | |
| <script src="//d3js.org/d3.v3.min.js"></script> | |
| <script> | |
| var margin = {top: 230, right: 30, bottom: 230, left: 30}, | |
| width = 960 - margin.left - margin.right, | |
| height = 500 - margin.top - margin.bottom; | |
| var n = 240, | |
| index = d3.range(n), | |
| data = shuffle(index.slice()); | |
| var x = d3.scale.ordinal().domain(index).rangePoints([0, width]), | |
| a = d3.scale.linear().domain([0, n - 1]).range([-Math.PI / 4, Math.PI / 4]); | |
| var svg = d3.select("body").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 + height) + ")"); | |
| var line = svg.selectAll("line") | |
| .data(data) | |
| .enter().append("line") | |
| .attr("index", function(d, i) { return "i" + i; }) | |
| .attr("x2", function(d) { return height * Math.sin(a(d)); }) | |
| .attr("y2", function(d) { return -height * Math.cos(a(d)); }) | |
| .attr("transform", function(d, i) { return "translate(" + x(i) + ")"; }); | |
| // Fisher–Yates shuffle | |
| function shuffle(array) { | |
| var i = array.length, j, t; | |
| while (--i > 0) { | |
| j = ~~(Math.random() * (i + 1)); | |
| t = array[j]; | |
| array[j] = array[i]; | |
| array[i] = t; | |
| } | |
| return array; | |
| } | |
| function quicksort(array) { | |
| var actions = []; | |
| 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; | |
| actions.push({type: "swap", i: i, j: j}); | |
| } | |
| function recurse(left, right) { | |
| if (left < right) { | |
| var pivot = left + ~~(Math.random() * (right - left)); | |
| actions.push({type: "partition", pivot: pivot}); | |
| pivot = partition(left, right, pivot); | |
| recurse(left, pivot); | |
| recurse(pivot + 1, right); | |
| } | |
| } | |
| recurse(0, array.length); | |
| return actions; | |
| } | |
| var actions = quicksort(data).reverse(); | |
| setInterval(function step() { | |
| var action = actions.pop(); | |
| if (action) switch (action.type) { | |
| case "partition": { | |
| line.style("stroke", function(d, i) { return i == action.pivot ? "red" : null; }); | |
| step(); | |
| break; | |
| } | |
| case "swap": { | |
| var t = line[0][action.i]; | |
| line[0][action.i] = line[0][action.j]; | |
| line[0][action.j] = t; | |
| line.attr("transform", function(d, i) { return "translate(" + x(i) + ")"; }); | |
| break; | |
| } | |
| } | |
| }, 20); | |
| </script> |
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