2027. Minimum Moves to Convert String

Problem

You are given a string s consisting of n characters which are either 'X' or 'O'.

A move is defined as selecting three consecutive characters of s and converting them to 'O'. Note that if a move is applied to the character 'O', it will stay the same.

Return **the *minimum* number of moves required so that all the characters of s are converted to **'O'.

  Example 1:

Input: s = "XXX"
Output: 1
Explanation: XXX -> OOO
We select all the 3 characters and convert them in one move.

Example 2:

Input: s = "XXOX"
Output: 2
Explanation: XXOX -> OOOX -> OOOO
We select the first 3 characters in the first move, and convert them to 'O'.
Then we select the last 3 characters and convert them so that the final string contains all 'O's.

Example 3:

Input: s = "OOOO"
Output: 0
Explanation: There are no 'X's in s to convert.

  Constraints:

• 3 <= s.length <= 1000

• s[i] is either 'X' or 'O'.

Solution (Java)

class Solution {
    public int minimumMoves(String s) {
        int r = 0;
        int i = 0;
        char[] sArray = s.toCharArray();
        while (i < sArray.length) {
            if (sArray[i] == 'X') {
                r++;
                i += 2;
            }
            i++;
        }
        return r;
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).