#include <stdio.h>
#include <vector>
#include <queue>
using namespace std;
int N,M;
vector< pair<int,int> > adj[100010];
vector<int> dijkstra(int src)
{
vector<int> dist(N+1,1234567890);
dist[src]=0;
priority_queue< pair<int,int> > pq;
pq.push(make_pair(0,src));
while(!pq.empty()){
int cost=-pq.top().first;
int here=pq.top().second;
pq.pop();
if(dist[here]<cost)continue;
for(int i=0;i<adj[here].size();++i){
int there=adj[here][i].first;
int nextDist=cost+adj[here][i].second;
if(dist[there]>nextDist){
dist[there]=nextDist;
pq.push(make_pair(-nextDist,there));
}
}
}
return dist;
}
int main()
{
int i,a,b;
scanf("%d %d",&N,&M);
for(i=1;i<=M;i++){
scanf("%d %d",&a,&b);
adj[a].push_back(make_pair(b,1));
}
vector<int> shortest=dijkstra(1);
int ret=shortest[N];
if(ret==1234567899)printf("-1\n");
else printf("%d\n",ret);
return 0;
}
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Incorrect |
0 ms |
3580 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
결과 |
실행 시간 |
메모리 |
Grader output |
| 1 |
Halted |
0 ms |
0 KB |
- |
