Reverse String

• Reverse String
  • 题目描述
  • 解法

Reverse String

题目描述

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

Example: Given s = "hello", return "olleh".

解法

代码如下:

public String reverseString(String s) {
    char[] cstr = s.toCharArray();
    int low = 0, high = cstr.length-1;
    while( low < high ) {
        char c = cstr[low];
        cstr[low++] = cstr[high];
        cstr[high--] = c;
    }
    return new String( cstr );
}

思考过程:

题目要求是翻转字符串, 方法是使用头尾指针交换字符.

首先头指针指向待交换字母, 然后尾指针也指向待交换字母, 最后交换头尾指针元素.

时空复杂度: 时间复杂度是O(n), 空间复杂度是O(n)