UVa 108

最大连续和的二维版本，貌似叫最大矩阵和，裸的，有多组数据.一开始写O(N^4)，一直WA，后来去学习O(N^3)的写法，貌似也是DP，方程不会写，AC.

BTW，RQNOJ 106也是最大矩阵和.

 

[Code]

#include<iostream>using namespace std;int a[110][110] = {0};int main(){ int n, i, j, k, tmp, sum; while (scanf("%d", &n) == 1) { for (j = 1; j <= n; j++) for (i = 1; i <= n; i++) { cin >> a[i][j]; a[i][j] += a[i-1][j]; } sum = a[1][1]; for (i = 0; i <= n; i++) for (j = i; j <= n; j++) { tmp = 0; for (k = 1; k <= n; k++) { if (tmp < 0) tmp = a[j][k] - a[i][k]; else if (i != j) tmp += a[j][k] - a[i][k]; if (tmp > sum && tmp != 0) sum = tmp; } } cout << sum << endl; }}