LeetCode 344. Reverse String

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本文介绍了一个用于反转输入字符串的Java方法实现。通过将字符串转换为字符数组并利用双指针技术进行原地交换，实现了字符串的高效反转。此方法的时间复杂度为O(n)，空间复杂度也为O(n)。

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LeetCode 344. Reverse String

Description

Write a function that takes a string as input and returns the string reversed.

Example:
Given s = “hello”, return “olleh”.

    class Solution {
        public String reverseString(String s) {
            char[] str = s.toCharArray();
            int h = s.length() - 1;
            int l = 0;

            while (l < h) {
                char tmp = str[l];
                str[l] = str[h];
                str[h] = tmp;
                l++;
                h--;
            }
            return new String(str);
        }
    }

Complexity Analysis

Time Complexity: O(n) (Average Case) and O(n) (Worst Case) where n is the total number character in the input string. The algorithm need to reverse the whole string.

Auxiliary Space: O(n) space is used where n is the total number character in the input string. Space is needed to transform string to character array.