[Blue Bridge Cup 2018 finals] version branch

 

Reference blog: https: //blog.csdn.net/daixinliangwyx/article/details/90300400

A super memory. . . . . . (Available advise Kazakhstan)

 I address the topic submitted by: http://oj.ecustacm.cn/problem.php?id=1400

 

#include <iostream>
#include <cstring> 
#include <vector>
#include <queue>
#include <algorithm>


using namespace std;

const  int L = 100009 ;
vector<int> child[L];
vector<int> data[L];
int N,Q; 

vector<int> getChild(int node) {
    for (int i = 0; i < data[node].size(); i++) {
        vector<int> chs = getChild(data[node][i]);
        child[node].insert(child[node].end(), chs.begin(), chs.end());
    }
    child[node].push_back(node);
    return child[node];
}

int main () {
    
    int p,s;
    while(~scanf("%d%d", &N, &Q)) {
        for (int i = 1; i < N; i++) {
            scanf("%d%d", &p, &s);
            data[p].push_back(s);
            
        }
        
        child[1] = getChild(1);
        
        for (int i = 1; i <= Q; i++) {
            scanf("%d%d", &p, &s);
            vector<int>::iterator it = find(child[p].begin(), child[p].end(), s);
            
            if (it != child[p].end()) {
                cout << "YES" << endl;
            } else {
                cout << "NO" << endl;
            }
        }
    
        for (int i = 0; i < L; i++) {
            data[i].clear();
            child[i].clear();
        }
    }
    
    return 0;
}

 

 

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