Reverse Prefix of Word Problem
Description
LeetCode Problem 2000.
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:
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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:
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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:
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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.
Sample C++ Code
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string reversePrefix(string word, char ch) {
auto p = word.find(ch);
if (p != string::npos)
reverse(begin(word), begin(word) + p + 1);
return word;
}