20180613更新 leetcode刷题

最近就是忙工作项目 工作间隙就刷了刷LEETCODE 所以没啥更新

 // 1111111.cpp: 定义控制台应用程序的入口点。
 //

 #include "stdafx.h"
 #include <vector>
 #include <queue>

 using namespace std;

 bool canFinish1(int numCourses, vector<vector<int>>& prerequisites) {
     vector<vector<int> > graph(numCourses, vector<int>());
     vector<int> in(numCourses, );
     for (auto a : prerequisites) {
         graph[a[]].push_back(a[]);
         ++in[a[]];
     }
     queue<int> q;
     for (int i = ; i < numCourses; ++i) {
         if (in[i] == ) q.push(i);
     }
     while (!q.empty()) {
         int t = q.front();
         q.pop();
         for (auto a : graph[t]) {
             --in[a];
             if (in[a] == ) q.push(a);
         }
     }
     for (int i = ; i < numCourses; ++i) {
         if (in[i] != ) return false;
     }
     return true;
 }

 //==========================================================================

 bool canFinishDFS(vector<vector<int> > &graph, vector<int> &visit, int i) {
     if (visit[i] == -) return false;
     if (visit[i] == ) return true;
     visit[i] = -;
     for (auto a : graph[i]) {
         if (!canFinishDFS(graph, visit, a)) return false;
     }
     visit[i] = ;
     return true;
 }

 bool canFinish2(int numCourses, vector<vector<int> >& prerequisites) {
     vector<vector<int> > graph(numCourses, vector<int>());
     vector<int> visit(numCourses, );
     for (auto a : prerequisites) {
         graph[a[]].push_back(a[]);
     }
     for (int i = ; i < numCourses; ++i) {
         if (!canFinishDFS(graph, visit, i)) return false;
     }
     return true;
 }

 int main()
 {
     //测试数据
     {
         int i = ;
         vector<vector<int> > v;
         v.push_back(std::vector<int>{, });
         v.push_back(std::vector<int>{ ,});
         canFinish1(i , v);
     }
     //{
     //    int i = 2;
     //    vector<vector<int> > v;
     //    v.push_back(std::vector<int>{1, 0});
     //    v.push_back(std::vector<int>{0, 1});
     //}
     //{
     //    int i = 2;
     //    vector<vector<int> > v;
     //    v.push_back(std::vector<int>{1, 0});
     //}
     //{
     //    int i = 3;
     //    vector<vector<int> > v;
     //    v.push_back(std::vector<int>{1, 0});
     //    v.push_back(std::vector<int>{2, 0});
     //}

 //    {
 //        int i = 3;
 //        vector<vector<int> > v;
 //        v.push_back(std::vector<int>{1, 0});
 //        v.push_back(std::vector<int>{2, 0});
 //    }
 //
 //    {
 //        int i = 3;
 //        vector<vector<int> > v;
 //        v.push_back(std::vector<int>{0, 1});
 //        v.push_back(std::vector<int>{1, 2});
 //    }
 //
 //    {
 //        int i = 4;
 //        vector<vector<int> > v;
 //        v.push_back(std::vector<int>{0, 1});
 //        v.push_back(std::vector<int>{1, 2});
 //        v.push_back(std::vector<int>{2, 0});
 //        v.push_back(std::vector<int>{1, 3});
 //    }
 //
 //    {
 //        int i = 4;
 //        vector<vector<int> > v;
 //        v.push_back(std::vector<int>{0, 1});
 //        v.push_back(std::vector<int>{1, 2});
 //        v.push_back(std::vector<int>{1, 3});
 //    }

     return ;
 }

leetcode 207