1045. 箱子打包

#include <iostream>
#include <algorithm>
using namespace std;
const int maxn = 1e5+5;
int arr[maxn];

int main() {
    int n,l,ans=0;
    cin>>n>>l;
    for (int i = 0; i < n; ++i) {
        cin>>arr[i];
    }
    sort(arr,arr+n);
    int left=0,right=n-1;
    while(left<=right){
        if (left == right){
            ans++;
            break;
        }
        if (arr[left]+arr[right]<=l){
            ans++;
            left++;
            right--;
        }else{
            ans++;
            right--;
        }
    }
    cout<<ans<<endl;
    return 0;
}