T3811.魔法【代码】
2023-08-21 09:44:03
发布于：浙江
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#include <map>
#include <set>
#include <queue>
#include <stack>
#include <cmath>
#include <vector>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const double PI = acos(-1);
const ll N=1e3+5;
int n,m;
ll dp[N][N];
int main(){
freopen("magic.in","r",stdin);
freopen("magic.out","w",stdout);
cin >> n>> m;
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
if(i!=j)
dp[i][j] = 2147483647;
}
}
for(int i=1;i<=m;i++){
int u,v;
cin >> u >> v;
dp[u][v] = 1;
}
for(int k=1;k<=n;k++){
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
dp[i][j] = min(dp[i][j],dp[i][k]+dp[k][j]);
}
}
}
int x,y;
cin >> x >> y;
if(dp[x][y] == 2147483647){
cout << "-1";
}else{
cout <<dp[x][y];
}
fclose(stdin);
fclose(stdout);
return 0;
}
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