Calculate sum of remaining squares in current row by removing the leftmost strip of previous sub - square and adding a new strip
for ( int j = 1 ; j < n - k + 1 ; j ++ ) { sum += ( stripSum [ i , j + k - 1 ] - stripSum [ i , j - 1 ] ) ; Console . Write ( sum + " ▁ " ) ; } Console . WriteLine ( ) ; } }