//大概用js实现一下迪克斯特拉算法，计算最短路径

        // （6）→ A → (1)

        //   ↑    ↑    ↓

        // 起点  (3)  终点

        //   ↓    ↑    ↑

        //  (2) → B → (5)

        //迪克斯特拉算法只适用于有向无环图，且没有负权重

        //上图()内为权重

        //散列表在js中表示为对象

        var graph = {};//记录节点

        graph.start = {};

        graph.start.a = 6;//起点到达A点权重为6

        graph.start.b = 2;

        graph.a = {};

        graph.a.end = 1;

        graph.b = {};

        graph.b.end = 5;

        graph.b.a = 3;

        graph.end = {};

        var costs = {};//记录起点到各点权重

        costs.a = 6;

        costs.b = 2;

        costs.end = '';//暂时不知道

        var parents = {};//记录最短路径中各节点的父节点

        parents.a = 'start';

        parents.b = 'start';

        parents.end = '';

        var processed = {};//记录已处理过的节点

        //找出开销最小的节点(方法比较多呢，随便写了一个)

        function findLowestCostNode(costs) {

            var value = '';

            var node = '';

            for(var key in costs) {

                if(processed[key]) {

                    continue;

                }

                if(!value) {

                    value = costs[key];

                    node = key;

                }else {

                    if(costs[key] && costs[key]<value) {

                        value = costs[key];

                        node = key;

                    }

                }

            }

            return node;

        }

        var node = findLowestCostNode(costs);//找出开销最小节点

        while(node) {

            var cost = costs[node];//当前最小开销

            var neighbors = graph[node];//当前节点相邻节点

            for(var n in neighbors) {

                var newCost = cost + neighbors[n];//到达相邻节点的开销数

                if (!costs[n]) {

                    costs[n] = newCost;

                    parents[n] = node;

                }else {

                    if (costs[n] > newCost) {//检查相应节点开销数是否小于已知开销数

                        costs[n] = newCost;//更新相应节点开销数

                        parents[n] = node;//更新相应节点父节点

                    }

                }

            }

            processed[node] = 1;;//记录已处理过节点

            node = findLowestCostNode(costs);//更新最小节点继续循环

        }

        console.log(costs['end']);//6  此处为最短路径开销

        var line = [];

        line.unshift('end');

        printLine(parents['end']);

        console.log(line);//["start", "b", "a", "end"]

        //使用递归打印出完整路径

        function printLine(node) {

            if( node != 'start') {

                line.unshift(node);

                printLine(parents[node]);

            }else {

                line.unshift('start');

            }

        }