东华OJ：纪念品分组

#include <bits/stdc++.h>
using namespace std;
//贪心算法，两头往中间靠拢 
int main() {
    int w, n;
    cin>>w>>n;
    int a[n];
    for(int i = 0; i < n; i++)
        scanf("%d", &a[i]);
    sort(a, a+n);
    int i = 0, j = n-1, cnt = 0;
    while(i <= j) {
        if(a[i] + a[j] <= w) {
            i++;
        }
        cnt++;
        j--;
    }
    cout << cnt;
    return 0;
}