Submission #229964

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
#define all(c) (c).begin(),(c).end()
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;i--)
#define REP(i,m,n) for(int i=(int)(m);i<(int)(n);i++)
#define iter(c) __typeof((c).begin())
#define tr(it,c) for(iter(c) it=(c).begin();it!=(c).end();it++)
#define pb(a) push_back(a)
#define pr(a) cout<<(a)<<endl
#define PR(a,b) cout<<(a)<<" "<<(b)<<endl
#define F first
#define S second
#define ll long long
bool check(int n,int m,int x,int y){return (x<0||x>=n||y<0||y>=m)?false:true;}
const ll MAX=1000000007,MAXL=1LL<<60,dx[4]={-1,0,1,0},dy[4]={0,-1,0,1};
typedef pair<int,int> P;
struct edge {int to, cost;};
int main() {
  int n;
  cin >> n;
  vector<edge> v[n+1];
  rep(i,n-1) {
    int x,y;
    cin >> x >> y;
    edge e;
    e.to=y;
    e.cost=1;
    v[x].pb(e);
    swap(x,e.to);
    v[x].pb(e);
  }
  int m;
  cin >> m;
  while(m--) {
    int a,b;
    cin >> a >> b;
    int d[n+1];
    fill(d,d+n+1,MAX);
    d[a]=0;
    queue<P> que;
    que.push(P(a,0));
    while(!que.empty()) {
      P p=que.front();
      que.pop();
      int x=p.F;
      if(x==b) break;
      if(d[x]<p.S) continue;
      rep(i,v[x].size()) {
	edge e=v[x][i];
	if(d[e.to]>d[x]+e.cost) {
	  d[e.to]=d[x]+e.cost;
	  que.push(P(e.to,d[e.to]));
	}
      }
    }
    pr(d[b]+1);
  }
  return 0;
}

Submission Info

Judge Result