(function (exports) {

'use strict';

var topologicalSort = (function () {

function topologicalSortHelper(node, visited, temp, graph, result) {

temp[node] = true;

var neighbors = graph[node];

for (var i = 0; i < neighbors.length; i += 1) {

var n = neighbors[i];

if (temp[n]) {

throw new Error('The graph is not a DAG');

}

if (!visited[n]) {

topologicalSortHelper(n, visited, temp, graph, result);

}

}

temp[node] = false;

visited[node] = true;

result.push(node);

}

/**

* Topological sort algorithm of a directed acyclic graph.<br><br>

* Time complexity: O(|E| + |V|) where E is a number of edges

* and |V| is the number of nodes.

*

* @public

* @module graphs/others/topological-sort

* @param {Array} graph Adjacency list, which represents the graph.

* @returns {Array} Ordered vertices.

*

* @example

* var topsort =

* require('path-to-algorithms/src/graphs/' +

* 'others/topological-sort').topologicalSort;

* var graph = {

* v1: ['v2', 'v5'],

* v2: [],

* v3: ['v1', 'v2', 'v4', 'v5'],

* v4: [],

* v5: []

* };

* var vertices = topsort(graph); // ['v3', 'v4', 'v1', 'v5', 'v2']

*/

return function (graph) {

var result = [];

var visited = [];

var temp = [];

for (var node in graph) {

if (!visited[node] && !temp[node]) {

topologicalSortHelper(node, visited, temp, graph, result);

}

}

return result.reverse();

};

}());

exports.topologicalSort = topologicalSort;

}(typeof exports === 'undefined' ? window : exports));