백준 2056번 작업 C++

https://www.acmicpc.net/problem/2056

2056번: 작업

 

위상 정렬

 

#include <iostream>
#include <string>
#include <vector>
#include <math.h>
#include <algorithm>
#include <utility>
#include <stack>
#include <queue>
#include <math.h>
#include <set>
#include <map>
#include <list>
#include <unordered_map>
#include <unordered_set>
#include <iomanip>
#include <limits.h>

using namespace std;
using int64 = long long;

int n;
vector<int> inDegree;
vector<int> times;
vector<int> res;
vector<vector<int>> graph;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);

    cin >> n;
    inDegree = vector<int>(n + 1, 0);
    times = vector<int>(n + 1);
    res = vector<int>(n + 1, 0);
    graph = vector<vector<int>>(n + 1, vector<int>());

    for (int i = 1; i <= n; i++) {
        int t;
        cin >> t;
        times[i] = t;
        int cnt;
        cin >> cnt;
        for (int j = 0; j < cnt; j++) {
            int before;
            cin >> before;
            graph[before].push_back(i);
            inDegree[i]++;
        }
    }
    queue<int> q;
    for (int i = 1; i <= n; i++) {
        if (inDegree[i] == 0) q.push(i);
    }
    int ans = 0;
    while (!q.empty()) {
        int curr = q.front();
        q.pop();
        for (auto next : graph[curr]) {
            res[next] = max(res[next], res[curr] + times[curr]);
            if (--inDegree[next] == 0) q.push(next);
        }
    }
    for (int i = 1; i <= n; i++) {
        res[i] += times[i];
        ans = max(ans, res[i]);
    }
    cout << ans;
}