BestCoder Round #43 HDU 5065 关于数字取余的问题

pog loves szh II

Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)

Total Submission(s): 459    Accepted Submission(s): 123

Problem Description Pog and Szh are playing games.There is a sequence with  n  numbers, Pog will choose a number A from the sequence. Szh will choose an another number named B from the rest in the sequence. Then the score will be  (A+B)  mod  p .They hope to get the largest score.And what is the largest score?  

Input Several groups of data (no more than  5  groups, n≥1000 ).

For each case: 

The following line contains two integers, n(2≤n≤100000) ， p(1≤p≤231−1) 。

The following line contains  n  integers  ai(0≤ai≤231−1) 。  

Output For each case,output an integer means the largest score.  

Sample Input

4 4
1 2 3 0
4 4
0 0 2 2
        

Sample Output

3
2
        

Source BestCoder Round #43       原文地址

  官方题解：

<span style="font-size:18px;">#include <algorithm>
#include <iostream>
#include <cstdio>
using namespace std;
typedef long long LL;
const int MAXN = 100010;
LL a[MAXN];

int main()
{
    int n, p;
    while (cin >> n >> p)
    {
        for (int i = 0; i < n; ++i)
        {
            scanf("%d", &a[i]);
            a[i] %= p;
        }
        sort(a, a+n);
        LL ans = (a[n-1]+a[n-2])%p;
        int i = 0, j = n-1;
        while (i < j)
        {
            if (a[i] + a[j] >= p)
                --j;
            else
            {
                ans = max(ans, a[i]+a[j]);
                ++i;
            }
        }
        cout << ans << endl;
    }
    return 0;
}</span>
           
   

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