# Lintcode:拓扑排序(深度优先搜索，广度优先搜索)

//广度优先搜索(BFS)

``vector<DirectedGraphNode*> topSort(vector<DirectedGraphNode*> graph) { vector<DirectedGraphNode*> ret; if(graph.empty()) return ret; map<DirectedGraphNode*,int> in; //in为入度 queue<DirectedGraphNode*> s; //保存入度为零的节点 for(auto e:graph){ for(auto i:e->neighbors) ++in[i]; //记录每个节点的入度 } for(auto e:graph) if(0==in[e]) s.push(e); //入度为零的节点入栈 while(!s.empty()){ //BFS遍历,搜寻入度为零的节点 DirectedGraphNode* cur=s.front(); s.pop(); //当前节点出栈时，它的相邻节点入度都减一 ret.push_back(cur); for(auto e:cur->neighbors){ if(--in[e]==0) //减一后为零则入栈 s.push(e); } } return ret; } ``

//深度优先搜索(DFS)

``bool search(vector<DirectedGraphNode*> &result, DirectedGraphNode* node) { for(auto p: result) { if(p == node) return 1; } return 0; } //DFS void dfs(DirectedGraphNode* graph, vector<DirectedGraphNode*> &result) { for(auto childgraph: graph->neighbors) { if(!search(result,childgraph)) dfs(childgraph, result); } result.push_back(graph); } vector<DirectedGraphNode*> topSort(vector<DirectedGraphNode*> graph) { // write your code here vector<DirectedGraphNode*> result; for(auto node : graph) { if(!search(result,node)) dfs(node, result); } reverse(result.begin(),result.end()); return result; }``

原文作者：拓扑排序
原文地址: https://blog.csdn.net/zyf19930610/article/details/55804741
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