HDU 1081 To The Max

转换成最大子序列和

#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>

#define MAX 200
using namespace std;

int main(){
    int n;
    while(cin >>n){
        int arr[MAX][MAX]={0};
        for(int i = 1; i<= n; i ++ ){
            for(int j = 1; j <= n; j ++ ){
                cin>>arr[i][j];
                arr[i][j] += arr[i-1][j];
            }
        }
        int maxSum =-1<<30 ;
        for(int i = 0; i < n; i ++ ){
            for(int j = i+1; j <= n; j ++){
                int thisSum = 0;
                for(int k = 1; k <= n; k ++){
                    thisSum += arr[j][k] - arr[i][k];
                    if(maxSum < thisSum) maxSum = thisSum;
                    else if(thisSum < 0) thisSum = 0;
                }
            }
        }
        cout<<maxSum<<endl;
    }
}