POJ 1050 求最大子矩阵和 动态规划

#include <iostream>
using namespace std;
int rec[102][102];
int b[100];
int main(){
	int n,k,s,sum,max;
	int i,j;
	cin>>n;
	for (i = 0;i < n;i++)
		for (j = 0;j < n;j++)
		{
			cin>> rec[i][j];
		}
	s = 0;
	for (i = 0;i < n;i++)
	{
		for (k = 0;k < n;k++)	b[k] = 0;
		for (j = i;j < n;j++)
		{
			for (k = 0;k < n;k++)
				b[k]+=rec[j][k];
			sum = 0;
			max = 0;
			for (k = 0;k < n;k++)
			{
				if (sum + b[k] > 0)
					sum+=b[k];
				else sum = b[k];
				if (sum > max)
					max = sum;
			}
			if (max > s)
				s = max;
		}
	}
	cout<<s<<endl;
	return 0;
}