ЗОШ Dijkstra OK

#include <iostream>
#include <cmath>
#include <vector>
#include <queue>
#include <algorithm>
#include <string>
#include <stack>
#include <set>
#include <map>
#define pii pair <int,int>
using namespace std;
using ll = long long;
using ld = long double;
using db = double;
void cv(vector <int> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}

void cvl(vector <ll> &v){
    for (auto x: v) cout<<x<<' ';
    cout<<"\n";
}


void cvv(vector <vector <int> > &v){
    for (auto x: v) cv(x);
    cout<<"\n";
}

struct ed{
    int fr, to;
    ld w;
};

vector < vector <ed> > G;



set <pii> Q;

vector <int> d;


const int inf  = 2e9;
int n,s,f;

void Dij(int s){

    d.assign(n, inf);

    //cv(d);

    Q.insert({0, s});

    d[s] = 0;

    while (!Q.empty()){
        int v  = Q.begin()->second;

        Q.erase(Q.begin());
        for (ed e: G[v]){
            int nv = e.to;
            if (d[nv] > d[v] + e.w){
                Q.insert({d[v] + e.w, nv});
                d[nv] = d[v] + e.w;
            }
        }
    }
}

int main()
{
    ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);

	cin>>n>>s>>f;
	s--;
	f--;
	G.resize(n);
	for (int i = 0; i < n; ++i){
        for (int j = 0 ;j < n;++j){
            int di;
            cin>>di;
            if (i == j) continue;
            if (di == -1) continue;
            G[i].push_back({i, j, di});
        }
	}
	Dij(s);
	if (d[f] == inf){
        cout<<-1;
        exit(0);
	}
	cout<<d[f]<<"\n";
}
/*
3 1 2
0 -1 2
3 0 -1
-1 4 0


*/