leetcode-917-Reverse-Only-Letters

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描述

Given a string S, return the “reversed” string where all characters that are not a letter stay in the same place, and all letters reverse their positions.

Example 1:

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Input: "ab-cd"
Output: "dc-ba"

Example 2:

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Input: "a-bC-dEf-ghIj"
Output: "j-Ih-gfE-dCba"

Example 3:

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Input: "Test1ng-Leet=code-Q!"
Output: "Qedo1ct-eeLg=ntse-T!"

分析

双指针，从两边向中间靠近，将前后的字符进行交互，即可达到倒转的目的。

解决方案1(Java)

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class Solution {
    public String reverseOnlyLetters(String S) {
        char[] sCharsArray = S.toCharArray();
        int left = 0, right = sCharsArray.length - 1;
        while(left < right) {
            while(left < right && !Character.isLetter(sCharsArray[left])) {
                left++;
            }
            while(left < right && !Character.isLetter(sCharsArray[right])) {
                right--;
            }
            char tmp = sCharsArray[left];
            sCharsArray[left] = sCharsArray[right];
            sCharsArray[right] = tmp;
            left++;
            right--;
        }
        return new String(sCharsArray);
    }
}

题目来源