113 lines
2.4 KiB
JavaScript
113 lines
2.4 KiB
JavaScript
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/**
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* general topological sort
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* from https://gist.github.com/1232505
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* @author SHIN Suzuki (shinout310@gmail.com)
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* @param Array<Array> edges : list of edges. each edge forms Array<ID,ID> e.g. [12 , 3]
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*
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* @returns Array : topological sorted list of IDs
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**/
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function tsort(edges) {
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var nodes = {}, // hash: stringified id of the node => { id: id, afters: lisf of ids }
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sorted = [], // sorted list of IDs ( returned value )
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visited = {}; // hash: id of already visited node => true
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var Node = function(id) {
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this.id = id;
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this.afters = [];
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}
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// 1. build data structures
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edges.forEach(function(v) {
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var from = v[0], to = v[1];
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if (!nodes[from]) nodes[from] = new Node(from);
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if (!nodes[to]) nodes[to] = new Node(to);
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nodes[from].afters.push(to);
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});
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// 2. topological sort
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Object.keys(nodes).forEach(function visit(idstr, ancestors) {
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var node = nodes[idstr],
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id = node.id;
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// if already exists, do nothing
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if (visited[idstr]) return;
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if (!Array.isArray(ancestors)) ancestors = [];
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ancestors.push(id);
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visited[idstr] = true;
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node.afters.forEach(function(afterID) {
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if (ancestors.indexOf(afterID) >= 0) // if already in ancestors, a closed chain exists.
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throw new Error('closed chain : ' + afterID + ' is in ' + id);
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visit(afterID.toString(), ancestors.map(function(v) { return v })); // recursive call
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});
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sorted.unshift(id);
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});
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return sorted;
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}
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/**
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* TEST
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**/
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function tsortTest() {
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// example 1: success
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var edges = [
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[1, 2],
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[1, 3],
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[2, 4],
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[3, 4]
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];
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var sorted = tsort(edges);
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console.log(sorted);
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// example 2: failure ( A > B > C > A )
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edges = [
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['A', 'B'],
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['B', 'C'],
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['C', 'A']
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];
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try {
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sorted = tsort(edges);
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}
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catch (e) {
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console.log(e.message);
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}
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// example 3: generate random edges
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var max = 100, iteration = 30;
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function randomInt(max) {
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return Math.floor(Math.random() * max) + 1;
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}
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edges = (function() {
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var ret = [], i = 0;
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while (i++ < iteration) ret.push( [randomInt(max), randomInt(max)] );
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return ret;
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})();
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try {
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sorted = tsort(edges);
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console.log("succeeded", sorted);
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}
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catch (e) {
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console.log("failed", e.message);
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}
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}
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// for node.js
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if (typeof exports == 'object' && exports === this) {
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module.exports = tsort;
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if (process.argv[1] === __filename) tsortTest();
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}
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