标准题解

#include<bits/stdc++.h>
using namespace std;
const int MAX_N = 1000000;
int main() {
	int w,n;
	cin>>w>>n;
	int prices[MAX_N];
	for(int i = 0;i < n;i++) {
		cin>>prices[i];
	}
	sort(prices,prices + n);
	int count = 0;
	int left = 0,right = n - 1;
	while(left <= right){
		if(prices[left] + prices[right] <= w){
			left++;
			right--;
		}else{
			right--;
		}
		count++;
	}
	cout<<count;    
	return 0;
}