2000.go

// Source: https://leetcode.com/problems/reverse-prefix-of-word
// Title: Reverse Prefix of Word
// Difficulty: Easy
// Author: Mu Yang <http://muyang.pro>
//
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// 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.
//
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package main

import "slices"

func reversePrefix(word string, ch byte) string {
	bytes := []byte(word)

	idx := slices.Index(bytes, ch)
	for i := 0; i <= idx; i++ {
		bytes[i] = word[idx-i]
	}

	return string(bytes)
}