Question

I have a two dimensional array and also have the start and end point. The array is initialized to zero and i have to update from the start to end position with one. What is the best algorithm to do it ?

For example if start and end position are (2,2) and (4,2) i need to start updating the values from 2,2 and end at 4,2. Rest of the array should be zero.

Answer 1

Just loop over the array from start index to end index.

for(int i = startCol; i <= endCol; i++) {
   for(int j = startRow; j <= endRow; j++) {
       a[i][j] = 1;
   }
}

it’s going to take O(n^2) time but I think that’s the best you can do.