백준 1956번 운동 C++

https://www.acmicpc.net/problem/1956

1956번: 운동

 

플로이드-워셜

 

#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 v, e;
vector<vector<int>> graph;

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

    cin >> v >> e;
    graph = vector<vector<int>>(v + 1, vector<int>(v + 1, -1));
    for (int i = 0; i < e; i++) {
        int a, b, c;
        cin >> a >> b >> c;
        graph[a][b] = c;
    }

    for (int k = 1; k <= v; k++) {
        for (int i = 1; i <= v; i++) {
            for (int j = 1; j <= v; j++) {
                if (graph[i][k] == -1) continue;
                if (graph[k][j] == -1) continue;
                if (graph[i][j] == -1) graph[i][j] = graph[i][k] + graph[k][j];
                else graph[i][j] = min(graph[i][j], graph[i][k] + graph[k][j]);
            }
        }
    }
    
    bool ans = false;
    int dist = 987654321;
    for (int i = 1; i <= v; i++) {
        if (graph[i][i] == -1) continue;
        ans = true;
        dist = min(dist, graph[i][i]);
    }

    if (ans) cout << dist;
    else cout << -1;
}