[数据结构与算法]递归算法简述

普通

509. 斐波那契数

class Solution {
    public int fib(int n) {
         
        if (n == 0 || n == 1){
            return n;
        }else {
            return fib(n-1)+fib(n-2);
        }

    }

}

链表递归

if (head == null || head.next == null) {
     return head;
}
ListNode newHead = reverseList(head.next);
head.next.next = head;
head.next = null;
//建立新的链表
return newHead;

反转字符串

class Solution {
    public void reverseString(char[] s) {
        if(s == null || s.length == 0){
            return;
        }
        Change(s,0,s.length -1);

    }
    public void Change(char[] s , int left , int right){
        if(left >= right){
            return;
        }
        Change(s, left+1 , right-1);
        char temp = s[left];
        s[left] = s[right];
        s[right] = temp;

    }

}