#include<stdint.h>
#include<vector>
#include<queue>
std::vector<int> route[100000];
int length[100000];
int main(void)
{
std::queue<int> queue;
int N, M, x, y,min = -1;
scanf("%d %d", &N, &M);
for (int i = 0; i < M; i++)
{
scanf("%d %d", &x, &y);
route[x - 1].push_back(y - 1);
}
queue.push(0);
for (int l = 0;!queue.empty(); l++)
{
int size = queue.size();
for (int i = 0; i < size; i++)
{
int n = queue.front();
queue.pop();
if (length[n]!=0 && length[n]<l)
{
continue;
}
length[n] = l;
if (n == N - 1)
{
min = l;
}
for (int j = 0; j < route[n].size(); j++)
{
queue.push(route[n][j]);
}
}
}
printf("%d",min);
return 0;
}
Compilation message
Y.cpp: In function 'int main()':
Y.cpp:13:23: error: 'scanf' was not declared in this scope
Y.cpp:42:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
Y.cpp:48:17: error: 'printf' was not declared in this scope
