LintCode_拓扑排序_BFS实现

上一篇的文章是用DFS解决的，但如果遇到大规模图的时候会容易引起栈溢出，所以采用不涉及递归的BFS是个不错的选择。

#include <algorithm>using namespace std;/** * Definition for Directed graph. * struct DirectedGraphNode { *     int label; *     vector<DirectedGraphNode *> neighbors; *     DirectedGraphNode(int x) : label(x) {}; * }; */const int MAX=99999;class Solution {public:    /**     * @param graph: A list of Directed graph node     * @return: Any topological order for the given graph.     */    bool Visited[MAX]; //标记是否被加入    int inque[MAX]; //入度    queue<DirectedGraphNode*> temp; //辅助用的队列    vector<DirectedGraphNode*> result;    void bfs(DirectedGraphNode* r)  //广度优先搜索法，参数r是入度为0的结点    {        DirectedGraphNode* s;        temp.push(r);        Visited[r->label]=true;        while(!temp.empty())        {            s=temp.front(); temp.pop();            result.push_back(s); //将入度为0的点的label加入vector            //遍历邻居            for(int i=0;i<s->neighbors.size();i++)            {                inque[s->neighbors[i]->label]--;                if(inque[s->neighbors[i]->label]==0&&Visited[s->neighbors[i]->label]==false)                {                    Visited[s->neighbors[i]->label]=true;                    temp.push(s->neighbors[i]);                }            }        }    }    vector<DirectedGraphNode*> topSort(vector<DirectedGraphNode*> graph) {        for(int i=0;i<graph.size();i++)  //初始化数据        {                inque[graph[i]->label]=0;                Visited[graph[i]->label]=false;        }                for(int i=0;i<graph.size();i++)  //统计每个节点的入度            for(int j=0;j<graph[i]->neighbors.size();j++)                inque[graph[i]->neighbors[j]->label]++;                        for(int i=0;i<graph.size();i++)        {            if(inque[graph[i]->label]==0&&Visited[graph[i]->label]==false)                bfs(graph[i]);        }        return result;    }};