Envío 1405

Código

#include <iostream>

using namespace std;

int main() {
  int R, C;
  cin >> R;
  cin >> C;
  int a[R][C];
  int s[R][C];
  for (int r = 0; r < R; r++) {
    for (int c = 0; c < C; c++) {
      cin >> a[r][c];
		// calculate the summed-area table
		int sum = a[r][c];
		if(r-1>=0) sum += s[r-1][c];
		if(c-1>=0) sum += s[r][c-1];
		if(c-1>=0 and r-1>=0) sum -= s[r-1][c-1];
		s[r][c]= sum;
    }
  }
  int answer = s[0][0];
  for (int r0 = 0; r0 < R; r0++) {
    for (int r1 = r0; r1 < R; r1++) {
		for (int c0 = 0; c0 < C; c0++) {
		  for (int c1 = c0; c1 < C; c1++) {
          int sum = s[r1][c1];
          if(r0>0) sum -= s[r0-1][c1];
          if(c0>0) sum -= s[r1][c0-1];
          if(c0>0 and r0 > 0) sum += s[r0-1][c0-1];
          answer = max(sum, answer); 
		  }
		} 
    }
  }
  cout << answer << endl;
  return 0;
}