算法竞赛入门经典（第八章）

#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
	int n, m, mi;
	int w[100005];
	int num;
	int l, r;
	cin>>n>>m;
	for(int i = 1; i <= n; i++)
	{
		cin>>w[i];
	}
	sort(w+1, w+n+1);
	l = 1 , r = n;
	num = 0;
	while(l!=r)
	{
		mi = m;
		if(w[l] <= mi)
		{
			mi-=w[l];			
			l++;
		}	
		else
		{
			cout<<"No Answer!"<<endl;
			return 0;
		}
		if(w[r] <= mi)	r--;
		num++;
	}
	cout<<num<<endl;
	return 0;
}