dijkstra

#include <stdio.h>
#include <vector>
#include <utility>

using namespace std;

const int INF = 10000000;

int main(){
   int n, s, f;
   scanf("%d%d%d", &n, &s, &f);
   int tp;
   vector<vector<pair<int, int> > > g(n);
   for(int i = 0; i < n; ++i)
       for(int j = 0; j < n; ++j){
           scanf("%d", &tp);
           if(tp != -1 && i != j){
               g[i].push_back(make_pair(j, tp));
           }
       }
   vector<int> dist(n, INF);
   dist[s-1] = 0;
   vector<char> used(n, 0);
   for(int i = 0; i < n; ++i){
       int v = -1;
       for(int j = 0; j < n; ++j){
           if(!used[j] && (v == -1 || dist[j] < dist[v]))
               v = j;
       }
       used[v] = true;
       for(int j = 0; j < g[v].size(); ++j){
           int to = g[v][j].first;
           int len = g[v][j].second;
           if(!used[to] && dist[v] + len < dist[to])
               dist[to] = dist[v] + len;
       }
   }
   printf("%d\n", dist[f-1]);
   return 0;
}