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 + ;
 int a[MAXN], b[MAXN], c[MAXN], ab[MAXN], x[MAXN];
 int main()
 {
 //    freopen("in.txt", "r", stdin);

     int l, n, m;
     int cas = ;
     while (cin>>l>>n>>m) {
         cout<<"Case "<<++cas<<":"<<endl;
         for (int i=; i<l; i++) {
             cin>>a[i];
         }
         for (int i=; i<n; i++) {
             cin>>b[i];
         }
         int k = ;
         for (int i=; i<l; i++) {
             for(int j=; j<n; j++) {
                 ab[k++] = a[i] + b[j];
             }
         }
         k--;
         sort(ab, ab+k);
         for (int i=; i<m; i++) {
             cin>>c[i];
         }
         int s;
         cin>>s;
         for (int i=; i<s; ++i) {
             cin>>x[i];
         }
         for (int i=; i<s; i++) {
             int flag = ;
             for (int j=; j<m; ++j) {
                 int tmp = x[i] - c[j];
                 if (binary_search(ab, ab+k, tmp) == true) {
                     flag = ;
                     break;
                 }
             }
             if (flag) cout<<"YES"<<endl;
             else cout<<"NO"<<endl;
         }
     }
     return ;
 }