Xiao Sha's pain (thinking problem)

link ：https://ac.nowcoder.com/acm/contest/27740/G
source ： Cattle from

Correct code ：

#include <bits/stdc++.h>
using namespace std;
const int N=1e6+10;
int a[N];
int n,p;
int main()
{
    
	scanf("%d%d",&n,&p);
	for(int i=0;i<n;i++)
	{
    
		scanf("%d",&a[i]);
		a[i]=a[i]%p;
	}
	 
	sort(a,a+n);

	int maxn=(a[n-1]+a[n-2])%p;//  After the above treatment ,a[i]  Each number represented is less than p Number of numbers ,
	// And the sum of the last two numbers (a[n-1]+a[n-2]) Again %p, Will be the remainder of the ceiling , No one is older than him  
	int l=0,r=n-1;
	
	while(l<r)
	{
    
		if(a[l]+a[r]>=p)
		r--;
		else
		{
    
			maxn=max(maxn,a[l]+a[r]);
			l++;
		}
	 } 
	printf("%d\n",maxn);
	return 0;
}

Error timeout code ：

#include <bits/stdc++.h>
using namespace std;
const int N=1e6+10;
int a[N];
int n,p;
int main()
{
    
	scanf("%d%d",&n,&p);
	for(int i=0;i<n;i++)
	{
    
		cin>>a[i];
		a[i]=a[i]%p;
	}
	sort(a,a+n);
	long long minn=0;
	for(int i=0;i<n;)
	{
    
		for(int j=n-1;j>i;)
		{
    
			long long mm=(long long)(a[i]+a[j])%p;
			minn=max(minn,mm);
			if(mm<p)
			{
    
				i++;
				break;
			}
			else
			{
    
				j--;
			}
		}
	}
	printf("%lld\n",minn);
	return 0;
}