zoukankan      html  css  js  c++  java
  • [LC] 117. Populating Next Right Pointers in Each Node II

    Given a binary tree

    struct Node {
      int val;
      Node *left;
      Node *right;
      Node *next;
    }
    

    Populate each next pointer to point to its next right node. If there is no next right node, the next pointer should be set to NULL.

    Initially, all next pointers are set to NULL.

    Follow up:

    • You may only use constant extra space.
    • Recursive approach is fine, you may assume implicit stack space does not count as extra space for this problem. 

    Example 1:

    Input: root = [1,2,3,4,5,null,7]
    Output: [1,#,2,3,#,4,5,7,#]
    Explanation: Given the above binary tree (Figure A), your function should populate each next pointer to point to its next right node, just like in Figure B. The serialized output is in level order as connected by the next pointers, with '#' signifying the end of each level.

    /*
    // Definition for a Node.
    class Node {
        public int val;
        public Node left;
        public Node right;
        public Node next;
    
        public Node() {}
        
        public Node(int _val) {
            val = _val;
        }
    
        public Node(int _val, Node _left, Node _right, Node _next) {
            val = _val;
            left = _left;
            right = _right;
            next = _next;
        }
    };
    */
    class Solution {
        public Node connect(Node root) {
            Node cur = root;
            Node prev = null;
            Node head = null;
            while (cur != null) {
                while (cur != null) {
                    if (cur.left != null) {
                        if (prev != null) {
                            prev.next = cur.left;
                        } else {
                            head = cur.left;
                        }
                        prev = cur.left;
                    }
                    if (cur.right != null) {
                        if (prev != null) {
                            prev.next = cur.right;
                        } else {
                            head = cur.right;
                        }
                        prev = cur.right;
                    }
                    cur = cur.next;
                }
                cur = head;
                head = null;
                prev = null;
            }
            return root;
        }
    }
  • 相关阅读:
    react篇章-React State(状态)
    react篇章-React 组件-复合组件
    react篇章-React 组件-向组件传递参数
    react篇章-React 组件-ES6 class 来定义一个组件
    React篇章-React 组件
    复习常用算法_冒泡算法
    项目管理小结(如何做好一个百万级项目甚至千万级别的项目)
    AOP切点切面内容
    Spring 框架
    Spring MVC 框架
  • 原文地址:https://www.cnblogs.com/xuanlu/p/12185413.html
Copyright © 2011-2022 走看看