9. Таинство суммы

#include <iostream>
#include <algorithm>

using namespace std;

const int MAXN = 50000, MAX = 10000;
int a[MAXN], b[MAXN];
int n, k, m;

int main(int argc, char** argv) {
    ios_base::sync_with_stdio(0);
    cin >> n;
    for(int i = 0; i < n; ++i) {
        cin >> a[i];
    }
    cin >> k;
    for(int i = 0; i < k; ++i) {
        cin >> b[i];
    }
    sort(a, a+n);
    sort(b, b+k);
    for(int i = 0; i < n; ++i) {
        const int cur = a[i];
        int l = 0;
        int r = k;
        while(r-l > 1) { // binary search
            m = (l+r)>>1;
            if(cur+b[m] > MAX)
                r = m;
            else
                l = m;
        }
        if(cur + b[l] == MAX) {
            cout << "YES";
            return 0;
        }
    }
    cout << "NO";
}