【LeetCode】344. Reverse String

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本文介绍了一种通过不同方法实现字符串反转的Java程序。其中包括使用字符数组交换、StringBuilder类的reverse方法、位操作以及递归调用等四种方式。每种方法都有其特点，适合不同的应用场景。

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

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

public class ResverseString {
	public static String reverseString(String s) {
		if(s == null || s.length() < 2) 
			return s;
		char[] ch = s.toCharArray();
		int i = 0;
		int j = s.length() - 1;
		while (i < j) {
			char c = ch[i];
			ch[i] = ch[j];
			ch[j] = c;
			i++;
			j--;
		}
		return new String(ch);
	}
	
	public static String reverseStringB(String s) {
		return new StringBuilder(s).reverse().toString();
	}
	
	/**
	 * bit manipulation
	 * @param s
	 * @return
	 */
	public static String reverseStringC(String s) {
		byte[] bytes = s.getBytes();
		int i = 0;
		int j = s.length() - 1;
		while(i < j) {
			bytes[i] = (byte) (bytes[i] ^ bytes[j]);
			bytes[j] = (byte) (bytes[i] ^ bytes[j]); //bytes[i] ^ bytes[j] ^ bytes[j] = bytes[i];
			bytes[i] = (byte) (bytes[i] ^ bytes[j]); //bytes[i] ^ bytes[j] ^ bytes[i] = bytes[j];
			i++;
			j--;
		}
		return new String(bytes);
	}
	
	public static String reverseStringD(String s) {
		int len = s.length();
		if(len <= 1) return s;
		String leftStr = s.substring(0, len / 2);	
		String rightStr = s.substring(len / 2, len);
		return reverseString(rightStr) + reverseString(leftStr);
	}
	
	public static void main(String[] args) {
		String s = "hello";
		System.out.println(reverseString(s));
		System.out.println(reverseStringB(s));
		System.out.println(reverseStringC(s));
		System.out.println(reverseStringD(s));
	}
}