Reverse the letters in each word of the string, preserving word order and spaces.
Example 1
Input: s = "Mr Ding"
Output: "rM gniD"
Explanation: The word order is preserved.
Output: "rM gniD"
Explanation: The word order is preserved.
Example 2
Input: s = "Let's take LeetCode contest"
Output: "s'teL ekat edoCteeL tsetnoc"
Explanation:
Output: "s'teL ekat edoCteeL tsetnoc"
Explanation: