题解 | #最大子矩阵#

#include<cstdio>
#include<iostream>
#include<climits>
#define  N 100
using namespace std;
int com[N][N];
int total[N][N];
int dp[N];
int arr[N];
int MAXsub(int n){
    int maxium = -INT_MAX ;
    for(int i = 0 ; i<n ; ++i){
        if(i == 0){
            dp[i] = arr[i];
        }else{
            dp[i] = max(arr[i] ,dp[i-1] + arr[i]);
        }
        maxium = max(maxium,dp[i]);
    }
    return  maxium;
}

int Maxsubcom(int n){
    int maximal = -INT_MAX;
    for(int i = 0 ; i < n ; ++i){
        for(int j = i ; j < n ; ++j){
           for(int k = 0 ; k < n ;++k ){
               if( i ==0 ){
                   arr[k] = total[j][k];
               }else{
                   arr[k] = total[j][k] - total[i-1][k];
               }
           }
           int cur = MAXsub(n);
           maximal=max(maximal,cur);
        }

    }
    return maximal;
}
int main(){
    int n ;
    while(scanf("%d",&n) != EOF){
        for(int i = 0 ; i < n ; ++i){
            for(int j = 0 ; j < n ; ++j){
                scanf("%d",&com[i][j]);
            }
        }
        for(int i = 0 ; i < n ; ++i){
            for(int j = 0 ; j < n ; ++j){
                if(i == 0){
                    total[i][j] = com[i][j];
                }else{
                    total[i][j] = total[i-1][j] + com[i][j];//压缩矩阵使矩阵变为一位total数组
                }
            }
        }
        if( n == 1){
            printf("%d\n",com[0][0]);
        }else{
            int answer = Maxsubcom(n);
            printf("%d\n",answer);
        }
        
    }
    return 0;
}