Replace O's with X's
Medium Accuracy: 47.44% Submissions: 2586 Points: 4

Given a matrix mat of size N x M where every element is either ‘O’ or ‘X’.
Replace all ‘O’ with ‘X’ that are surrounded by ‘X’.
A ‘O’ (or a set of ‘O’) is considered to be by surrounded by ‘X’ if there are ‘X’ at locations just below, just above, just left and just right of it.

Example 1:

Input: n = 5, m = 4
mat = {{'X', 'X', 'X', 'X'}, 
       {'X', 'O', 'X', 'X'}, 
       {'X', 'O', 'O', 'X'}, 
       {'X', 'O', 'X', 'X'}, 
       {'X', 'X', 'O', 'O'}}
Output: ans = {{'X', 'X', 'X', 'X'}, 
               {'X', 'X', 'X', 'X'}, 
               {'X', 'X', 'X', 'X'}, 
               {'X', 'X', 'X', 'X'}, 
               {'X', 'X', 'O', 'O'}}
Explanation: Following the rule the above 
matrix is the resultant matrix. 

Your Task:
You do not need to read input or print anything. Your task is to complete the function fill() which takes n, m and mat as input parameters ad returns a 2D array representing the resultant matrix.

Expected Time Complexity: O(n*m)
Expected Auxiliary Space: O(n*m)

1 ≤ n, m ≤ 500

We are replacing the old Disqus forum with the new Discussions section given below.
Click here to view old Disqus comments.

to report an issue on this page.


We strongly recommend solving this problem on your own before viewing its editorial. Do you still want to view the editorial?


All Submissions

My Submissions:

Login to access your submissions.

Replace O's with X's

Output Window