2027. Minimum Moves to Convert String
Description
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'
.
Solutions
Solution 1: Greedy Algorithm
Traverse the string $s$. Whenever you encounter 'X'
, move the pointer $i$ three steps forward and add $1$ to the answer; otherwise, move the pointer $i$ one step forward.
The time complexity is $O(n)$, where $n$ represents the length of the string $s$.
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