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  1. #include<bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. int main() {
  6.     ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
  7.     int n, m; cin >> n >> m;
  8.     vector<vector<int> > a(n, vector<int>(m));
  9.     for (int i = 0; i < n; i++) {
  10.         for (int j = 0; j < m; j++) {
  11.             cin >> a[i][j];
  12.             if (j > 0) a[i][j] += a[i][j - 1]; // prefix sum for i-th row
  13.         }
  14.     }
  15.     int ans = 0;
  16.     for (int i = 0; i < m; i++) { // fix i
  17.         for (int j = i + 1; j < m; j++) { // fix j
  18.             int sum = 0;
  19.             for (int k = 0; k < n; k++) { // iterate from first row
  20.                 sum += a[k][j];
  21.                 if (i > 0) sum -= a[k][i - 1];
  22.                 ans = max(ans, sum);
  23.                 if (sum < 0) sum = 0;
  24.             }
  25.         }
  26.     }
  27.     cout << ans;
  28.     return 0;
  29. }
Success #stdin #stdout 0s 5660KB
comments (?)
stdin 
4 4
0 -2 -7 0
9 2 -6 2
-4 1 -4 1
-1 8 0 -2
stdout 
15
https://ideone.com/DgsqtC
2D max submatrix
language:
C++14 (gcc 8.3)
created:
3 years ago
visibility:
public

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