dijkstra求调全RE

#include<bits/stdc++.h>
using namespace std;
#define ll long long
struct edge {
    int to, weight;
    edge(int to, int weight) : to(to), weight(weight) {}
};
int n, m;
vector<vector<edge> > graph(n, vector<edge>());
vector<int> Dist(n,0);
vector<int> Prev(n,0);

void dijkstra(int source) {
    int n = graph.size();
    vector<bool> s(n, false);
    fill(Dist.begin(), Dist.end(), INT_MAX);
    fill(Prev.begin(), Prev.end(), -1);
    Dist[source] = 0;
    for (int i = 1; i <= n; i++) {
        int u = -1;
        for(int j = 1; j <= n; j++){
            if(!s[j] && (u == -1 || Dist[j] < Dist[u])){
                u = j;
            }
        }
        s[u] = 1;
        for(edge e:graph[u]){
            if(!s[u] && Dist[e.to] > Dist[u] + e.weight){
                Dist[e.to] = Dist[u] + e.weight;
                Prev[e.to] = u;
            }
        }
    }
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> n >> m;
    int source;
    cin >> source;
    for(int i = 1; i <= m; i++){
        int u, v, w;
        cin >> u >> v >> w;
        graph[u].push_back(edge(v, w));
    }
    dijkstra(source);
    for(int i = 1; i <= n; i++){
        cout << Dist[i];
    }
    return 0;
}