HDU1081 To The Max

二维前缀和 || 类子序列和的DP

后者快，压二维为一维的方法

#include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdio>

using namespace std;

const int N = 108;
int n, ans = -2147483633, up[N][N], dp[N], a, b[N];

int main()
{
    while (~scanf("%d", &n))
    {
        ans = -2147483633;
        for (int i = 1; i <= n; ++i)
            for (int j = 1; j <= n; ++j)
                scanf("%d", &a), up[i][j] = a + up[i - 1][j];
        for (int line = 1; line <= n; ++line)
            for (int high = 1; high <= line; ++high)
            {
                for (int i = 1; i <= n; ++i)
                    dp[i] = 0, b[i] = up[line][i] - up[high - 1][i];
                for (int i = 1; i <= n; ++i)
                    dp[i] = max(dp[i - 1], 0) + b[i], ans = max(dp[i], ans);
            }
        printf("%d
", ans);
    }
    return 0;
}