是个人都会做。 我能想到三种方法： // 1. two pointers, i < j // 2. j >= 0 ; j -- // 3. Stack

Here I implement the 3rd one:

public String reverse(String s) {		Stack
    
      stack = new Stack<>();		for (int i = 0; i < s.length(); i++) {			stack.push(s.charAt(i));		}		StringBuilder sb = new StringBuilder();		while (!stack.isEmpty()) {			sb.append(stack.pop());		}		return sb.toString();	}复制代码
    

有人实现了6种： https://discuss.leetcode.com/topic/43296/java-simple-and-clean-with-explanations-6-solutions