207. 课程表 (拓扑排序）

Posted 2022-06-23 code_kd

题目链接：https://leetcode-cn.com/problems/course-schedule/

解题代码：

class Solution 
public:
    bool canFinish(int numCourses, vector<vector<int>>& prerequisites) 
        vector<vector<int> > edges;
        edges.resize(numCourses);
        queue<int> q;
        int in[100000+5]=0;
        for(int i = 0;i<prerequisites.size();i++)
            edges[prerequisites[i][1]].push_back(prerequisites[i][0]);
            in[prerequisites[i][0]]++;
        
        //int cnt=0;
        for(int i = 0;i<numCourses;i++)
            if(in[i]==0)
                q.push(i);
                //cnt++;
                //break;
            
        
        if(q.empty()) return false;
        int cnt=0;
        while(!q.empty())
            int t = q.front();
            for(int i = 0;i<edges[t].size();i++)
                if(--in[edges[t][i]]==0)
                q.push(edges[t][i]);
            
            q.pop();
            cnt++;
        
        //cout<<cnt<<endl;
        return cnt==numCourses;
    
;