hdoj-2141-Can you find it?(二分查找)

题目链接

/*
    Name:HDU-2141-Can you find it?
    Copyright:
    Author:
    Date: 2018/4/12 17:15:46
    Description:
        暴力，复杂度n^3,不存在的
        将公式变换为A-B=X-C
        枚举A-B，复杂度n^2 
        二分查找复杂度O(log2n)，A-B是否存在A-B==X-C
*/
#include <iostream>
#include <algorithm> 
using namespace std;
const int MAXN = 1e6 + 10;
int a[MAXN], b[MAXN], c[MAXN], ab[MAXN], x[MAXN];
int main()
{
//    freopen("in.txt", "r", stdin);
    
    int l, n, m;
    int cas = 0;
    while (cin>>l>>n>>m) {
        cout<<"Case "<<++cas<<":"<<endl;
        for (int i=0; i<l; i++) {
            cin>>a[i];
        }
        for (int i=0; i<n; i++) {
            cin>>b[i];
        }
        int k = 0;
        for (int i=0; i<l; i++) {
            for(int j=0; j<n; j++) {
                ab[k++] = a[i] + b[j];
            }
        }
        k--;
        sort(ab, ab+k);
        for (int i=0; i<m; i++) {
            cin>>c[i];
        }
        int s;
        cin>>s;
        for (int i=0; i<s; ++i) {
            cin>>x[i];
        }
        for (int i=0; i<s; i++) {
            int flag = 0;
            for (int j=0; j<m; ++j) {
                int tmp = x[i] - c[j];
                if (binary_search(ab, ab+k, tmp) == true) {
                    flag = 1;
                    break;
                }
            }
            if (flag) cout<<"YES"<<endl;
            else cout<<"NO"<<endl;
        }
    }
    return 0;
}