https://leetcode-cn.com/problems/course-schedule/
class Solution {
private:
vector<vector<int>> edges;
vector<int> indeg;
public:
bool canFinish(int numCourses, vector<vector<int>>& prerequisites) {
edges.resize(numCourses);
indeg.resize(numCourses);
for (const auto& info: prerequisites) {
edges[info[1]].push_back(info[0]);
++indeg[info[0]];
}
queue<int> q;
for (int i = 0; i < numCourses; ++i) {
if (indeg[i] == 0) {
q.push(i);
}
}
int visited = 0;
while (!q.empty()) {
++visited;
int u = q.front();
q.pop();
for (int v: edges[u]) {
--indeg[v];
if (indeg[v] == 0) {
q.push(v);
}
}
}
return visited == numCourses;
}
};