A9. Декстра - 1

#include<iostream>
#include<vector>
#include<set>

using namespace std;

const int inf = (1 << 31) - 1;
int main ()
{
    int n,start,finish;
    cin >> n >> start >> finish;
    start--;finish--;
    vector <vector<pair<int,int>>> g(n);
    for ( int i = 0; i < n; i++)
    {
        for ( int j = 0; j < n; j++)
        {
           int w;
           cin >> w;
           if (w != -1 && i != j)
           {
               g[i].push_back({j,w});
           }
        }
     }

     vector <int> r(n,inf);
     r[start] = 0;
     set<pair<int,int>>s;
     s.insert({0,start});
     while (!s.empty())
     {
         int rmin = s.begin()->first;
         int cur = s.begin()->second;
         s.erase(s.begin());
        for (pair<int, int> to : g[cur])
        {
            if (r[cur] + to.second < r[to.first])
            {
				r[to.first] = r[cur] + to.second;
				s.insert({r[to.first], to.first});
			}
		}
     }
     if (r[finish] == inf)
        cout << -1;
     else
        cout << r[finish];
}