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>(0));
    vector<int> in(numCourses, 0);
    for (auto a : prerequisites) {
        graph[a[1]].push_back(a[0]);
        ++in[a[0]];
    }
    queue<int> q;
    for (int i = 0; i < numCourses; ++i) {
        if (in[i] == 0) q.push(i);
    }
    while (!q.empty()) {
        int t = q.front();
        q.pop();
        for (auto a : graph[t]) {
            --in[a];
            if (in[a] == 0) q.push(a);
        }
    }
    for (int i = 0; i < numCourses; ++i) {
        if (in[i] != 0) return false;
    }
    return true;
}

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

bool canFinishDFS(vector<vector<int> > &graph, vector<int> &visit, int i) {
    if (visit[i] == -1) return false;
    if (visit[i] == 1) return true;
    visit[i] = -1;
    for (auto a : graph[i]) {
        if (!canFinishDFS(graph, visit, a)) return false;
    }
    visit[i] = 1;
    return true;
}

bool canFinish2(int numCourses, vector<vector<int> >& prerequisites) {
    vector<vector<int> > graph(numCourses, vector<int>(0));
    vector<int> visit(numCourses, 0);
    for (auto a : prerequisites) {
        graph[a[1]].push_back(a[0]);
    }
    for (int i = 0; i < numCourses; ++i) {
        if (!canFinishDFS(graph, visit, i)) return false;
    }
    return true;
}


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