everse-prefix-of-word_2000.py

# Given a 0-indexed string word and a character ch, reverse the segment of word that starts at index 0 and ends at the index of the first occurrence of ch (inclusive). If the character ch does not exist in word, do nothing.

# For example, if word = "abcdefd" and ch = "d", then you should reverse the segment that starts at 0 and ends at 3 (inclusive). The resulting string will be "dcbaefd".
# Return the resulting string.

# Example 1:

# Input: word = "abcdefd", ch = "d"
# Output: "dcbaefd"
# Explanation: The first occurrence of "d" is at index 3.
# Reverse the part of word from 0 to 3 (inclusive), the resulting string is "dcbaefd".
# Example 2:

# Input: word = "xyxzxe", ch = "z"
# Output: "zxyxxe"
# Explanation: The first and only occurrence of "z" is at index 3.
# Reverse the part of word from 0 to 3 (inclusive), the resulting string is "zxyxxe".
# Example 3:

# Input: word = "abcd", ch = "z"
# Output: "abcd"
# Explanation: "z" does not exist in word.
# You should not do any reverse operation, the resulting string is "abcd".

# Constraints:

# 1 <= word.length <= 250
# word consists of lowercase English letters.
# ch is a lowercase English letter.

# ---------------------------------------Runtime 41 ms Beats 16.82% Memory 16.46 MB Beats 93.90%---------------------------------------


class Solution:
    def reversePrefix(self, word: str, ch: str) -> str:
        ch_index = word.find(ch)
        return word[: ch_index + 1][::-1] + word[ch_index + 1:]