#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,j,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;
}
Compilation message
Y.cpp:6:20: error: '>>' should be '> >' within a nested template argument list
Y.cpp: In function 'std::vector<int> dijkstra(int)':
Y.cpp:11:29: error: '>>' should be '> >' within a nested template argument list
Y.cpp:18:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
Y.cpp: In function 'int main()':
Y.cpp:31:8: warning: unused variable 'j' [-Wunused-variable]
Y.cpp:32:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
Y.cpp:34:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
