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CF609A USB Flash Drives

2022-07-16 08:37:00 【༺Blog༒Hacker༻】

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CF609A USB Flash Drives

题目描述
Sean is trying to save a large file to a USB flash drive. He has n USB flash drives with capacities equal to $a_{1},a_{2},...,a_{n}$ megabytes. The file size is equal to $m$ megabytes.
Find the minimum number of USB flash drives needed to write Sean’s file, if he can split the file between drives.

输入格式
The firstline contains positive integer $n (1 \leq n \leq 100) — —$ the number of USB flash drives.
The secondline contains positive integer $m ( 1≤m≤10^{5}) ——$ the size of Sean’s file.
Each of the next $n$ lines contains positive integer $a_{i} ( 1≤a_{i}≤1000 ) ——$ the sizes of USB flash drives in megabytes.
️ It is guaranteed that the answer exists, $i . e .$ the sum of all $a_{i}$ is not less than $m$ .

输出格式
Print the minimum number of USB flash drives to write Sean’s file, if he can split the file between drives.

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输入输出样例

输入 #1
3
5
2
1
3
输出 #1
2
输入 #2
3
6
2
3
2
输出 #2
3
输入 #3
2
5
5
10
输出 #3
1

说明/提示
️In the first example Sean needs only two USB flash drives — the first and the third.

️In the second example Sean needs all three USB flash drives.

️In the third example Sean needs only one USB flash drive and he can use any available USB flash drive — the first or the second.

思路

很简单的贪心模拟排序

CODE

#include<bits/stdc++.h>
#define ll long long
#define MAXN 1005
using namespace std;
ll n,m,a[MAXN],ans;
bool cmp(int x,int y)
{
    
    return x>y;
}
signed main()
{
    
	cin>>n>>m;
	for(int i=1;i<=n;++i)
	{
    
		cin>>a[i];
		sort(a+1,a+1+n,cmp);
	}
	for(int i=1;i<=n;++i)
	{
    
		m-=a[i];
		ans++;
		if(m<=0)
		  break;
	}
	cout<<ans<<endl;
	return 0;
}