AC记录https://hydro.ac/d/atcoder/record/66bf0a5db385d8ada2e01629

分析

cmp降序一排然后前$K$个相加

#include <bits/stdc++.h>
#include <algorithm>

#define endl '\n';


const int N = 1e6 + 10;
const int M = 2e6 + 10;
const int P = 998244353; 
const int Base = 3221225477;
const int INF = 0x3f3f3f3f3f3f3f3f; 

int mod(int x)
{
   return x % P;
}
bool cmp(int x,int y)
{
	return x > y;
}
using namespace std;
int n,k;
signed main()
{
	cin >> n >> k;
	int a[n];
	for(int i = 0;i < n;i++)
	{
		cin >> a[i];
	}
	sort(a,a+n,cmp);
	int sum = 0;
	for(int i = 0;i < k;i++)
	{
		sum+=a[i];
	}
	cout << sum << endl;
	
	return 0;
}