矩阵（二维数组）子矩阵最大和

#include<iostream>
#include<vector>
#include<limits.h>
#include<algorithm>
using namespace std;
//优化解法，O（N^3）

int maxSum(vector< vector<int> > &arr){
	if (arr.empty()){
		return 0;
	}

	int MAX = INT_MIN;  //记录全局最大值
	int cur = 0;
	for (int i = 0; i < arr.size(); i++){//二维数组名表示行向量
		
		vector<int> s(arr[0].size()); 
		//二维数组列向量的大小,每次都需要重新申请，否则会造成全局变量无法更新，
		//决策失败
		for (int j = i; j < arr.size(); j++){
			//[i.....j]列的范围
			cur = 0;
			for (int k = 0; k < s.size(); k++){   
			//有几行进行决策

				s[k] += arr[j][k];
				cur += s[k];
				MAX = max(MAX, cur);
				cur = cur < 0 ? 0 : cur;
				//cout << cur << endl;

			}
		}
	}
	return MAX;
}
int main(){

	vector< vector<int> > vec(2, vector<int>(4));
	int arr[] = { 3, 2, 1, 4, -6, 5, 2, -7 };
	int t = 0;
	for (int i = 0; i < 2; i++){
		for (int j = 0; j < 4; j++){
			vec[i][j] = arr[t++];
			//cout << vec[i][j] << endl;
		}
	}
	int res = maxSum(vec);
	cout << res << endl;
	

	return 0;
}#include<iostream>
#include<vector>
#include<li