c_cpp 数组中的max_sum矩形

Posted 2021-05-14

#include <bits/stdc++.h>
using namespace std;
#define ROW 4 
#define COL 5 
int kadane(int* arr, int* start, int* finish, int n){
	int sum = 0, maxSum = INT_MIN, i; 
	*finish = -1; 
    int local_start = 0;
    for(int i = 0;i < n;i++){
    	sum += arr[i];
    	if(sum < 0){
    		sum = 0;
    		local_start = i+1;
    	}
    	if(sum > maxSum){
    		maxSum = sum;
    		*start  = local_start;
    		*finish = i;
    	}
    }
    return maxSum;
}
void findMaxSum(int M[][COL]){
	int maxSum = INT_MIN, finalLeft, finalRight, finalTop, finalBottom; 
	int left, right, i;
	int temp[ROW], sum, start, finish; 
	for(left = 0;left < COL;++left){
		
		memset(temp,0,sizeof(temp));
		 for (right = left; right < COL; ++right) 
        { 
           for (i = 0; i < ROW; ++i){ 
                temp[i] += M[i][right]; 
           }
         sum = kadane(temp, &start, &finish, ROW); 
        
        if (sum > maxSum) 
            { 
                maxSum = sum; 
                finalLeft = left; 
                finalRight = right; 
                finalTop = start; 
                finalBottom = finish; 
            }
        }
            
	}
	cout << finalLeft << " "<< finalRight << endl;
	cout << finalTop << " " <<finalBottom << endl;
	
	cout <<maxSum << endl;
}
int main() {
	int M[ROW][COL] = {{1, 2, -1, -4, -20}, 
                       {-8, -3, 4, 2, 1}, 
                       {3, 8, 10, 1, 3}, 
                       {-4, -1, 1, 7, -6} 
                      }; 
  
    findMaxSum(M); 
	return 0;
}