1.​​题目链接​​。一个经典的DP，但是需要注意一下初始化的问题，因为负数可能存在，所以可能会上来把DP数组初始化为0是不合适的，所以先把它初始化为一个绝对值很大的负数即可。代码如下：

#include<bits/stdc++.h>
#include<iostream>
#include<algorithm>
using namespace std;
int a[21][1100];
int dp[21][1100];
const int inf = -999999999;
#pragma warning(disable:4996)
int n, m;
int  main()
{
  int T;
  scanf("%d", &T);
  while (T--)
  {
    memset(a, 0, sizeof(a));
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; i++)
    {
      for (int j = 1; j <= m; j++)
      {
        scanf("%d", &a[i][j]);
      }
    }
    for (int i = 0; i < m; i++)
    {
      dp[0][i] = inf;
    }
    for (int i = 0; i < n; i++)
    {
      dp[i][0] = inf;
    }
    dp[0][1] = dp[1][0] = 0;
    for (int i = 1; i <= n; i++)
    {
      for (int j = 1; j <= m; j++)
      {
        dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
        for (int k = 2; k <= m; k++)
        {
          if (j%k == 0) {
            dp[i][j] = max(dp[i][j], dp[i][j / k]);
          }
        }
        dp[i][j]+=a[i][j];
      }
    }
    printf("%d\n", dp[n][m]);
  }

}