#include <stdio.h>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <algorithm>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <stack>
#include <ctype.h>
#define p(x,y) pair<x, y>
#define pii pair<int, int>
#define v(x) vector<x>
#define q(x) queue<x>
#define pq(x) priority_queue<x>
#define uppq(x, comp) priority_queue<x, vector<x>, comp>
#define st(x) set<x>
#define m(x, y) map<x, y>
#define fi(s,e) for(int i=s;i<e;i++)
#define fj(s,e) for(int j=s;j<e;j++)
#define fk(s,e) for(int k=s;k<e;k++)
typedef long long int ll;
typedef unsigned long long int ull;
typedef __int128 ulll;
using namespace std;
int n,m;
int s,d,a,b;
v(int) pushvec;
v(v(int)) vec;
int dista[200010], distb[200010];
int dpdiv[200010];
void spreada(int x){
q(p(pii, int)) qu;
qu.push({{x,x}, 0});
while(!qu.empty()){
p(pii, int) now = qu.front();
qu.pop();
if(now.second > dista[now.first.first] && dista[now.first.first] != -1) continue;
dista[now.first.first]=now.second;
int sz = vec[now.first.first].size();
fi(0,sz){
int next = vec[now.first.first][i];
if(next == now.first.second || (dista[next]!=-1 && dista[next] < now.second+1)) continue;
qu.push({{next, now.first.first}, now.second+1});
}
}
return;
}
void spreadb(int x){
q(p(pii, int)) qu;
qu.push({{x,x}, 0});
while(!qu.empty()){
p(pii, int) now = qu.front();
qu.pop();
if(now.second > distb[now.first.first] && distb[now.first.first] != -1) continue;
distb[now.first.first]=now.second;
int sz = vec[now.first.first].size();
fi(0,sz){
int next = vec[now.first.first][i];
if(next == now.first.second && (distb[next]!=-1 && distb[next] < now.second+1)) continue;
qu.push({{next, now.first.first}, now.second+1});
}
}
return;
}
int find(int now){
if(dp[now]) return dp[now];
int sz = vec[now].size();
int ans = dista[now];
fi(0,sz){
int next = vec[now][i];
if(dista[next]==dista[now]-1 && dista[next]==distb[next]){
ans = min(ans, find(next));
}
}
return dp[now]=ans;
}
int main(void){
scanf("%d%d%d%d%d%d",&n,&m,&s,&d,&a,&b);
fi(0,n+1) vec.push_back(pushvec);
fi(0,m){
int s,e;
scanf("%d%d",&s,&e);
vec[s].push_back(e);
vec[e].push_back(s);
}
fi(1,n+1){
dista[i]=-1;
distb[i]=-1;
}
spreada(a);
spreadb(b);
int ans = min(dista[d]-dista[s], distb[d]-distb[s]);
if(dista[s]==distb[s] && distb[d]==distb[d]){
int divds, divdd;
divds = find(s);
divdd = find(d);
if(divds > divdd) ans--;
}
printf("%d\n", max(ans, -1));
return 0;
}
Compilation message
007.cpp: In function 'int find(int)':
007.cpp:76:5: error: 'dp' was not declared in this scope; did you mean 'd'?
76 | if(dp[now]) return dp[now];
| ^~
| d
007.cpp:85:9: error: 'dp' was not declared in this scope; did you mean 'd'?
85 | return dp[now]=ans;
| ^~
| d
007.cpp: In function 'int main()':
007.cpp:108:35: warning: self-comparison always evaluates to true [-Wtautological-compare]
108 | if(dista[s]==distb[s] && distb[d]==distb[d]){
| ~~~~~~~~^~~~~~~~~~
007.cpp:89:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
89 | scanf("%d%d%d%d%d%d",&n,&m,&s,&d,&a,&b);
| ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
007.cpp:94:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
94 | scanf("%d%d",&s,&e);
| ~~~~~^~~~~~~~~~~~~~
