首页 > 代码库 > LeetCode: Populating Next Right Pointers in Each Node [116]
LeetCode: Populating Next Right Pointers in Each Node [116]
【题目】
Given a binary tree
struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *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
.
Note:
- You may only use constant extra space.
- You may assume that it is a perfect binary tree (ie, all leaves are at the same level, and every parent has two children).
For example,
Given the following perfect binary tree,
1 / 2 3 / \ / 4 5 6 7
After calling your function, the tree should look like:
1 -> NULL / 2 -> 3 -> NULL / \ / 4->5->6->7 -> NULL
【题意】
给定一个二叉树,把同层的节点连接起来。题目保证输入的二叉树是完整二叉树
【思路】
【代码】
/** * Definition for binary tree with next pointer. * struct TreeLinkNode { * int val; * TreeLinkNode *left, *right, *next; * TreeLinkNode(int x) : val(x), left(NULL), right(NULL), next(NULL) {} * }; */ class Solution { public: void connect(TreeLinkNode *root) { if(root==NULL)return; TreeLinkNode*prev; TreeLinkNode*cur; queue<TreeLinkNode*>q1; queue<TreeLinkNode*>q2; q1.push(root); while(!q1.empty() || !q2.empty()){ prev=NULL; if(!q1.empty()){ while(!q1.empty()){ cur=q1.front(); q1.pop(); if(prev)prev->next=cur; prev=cur; //把下层节点保存到q2 if(cur->left)q2.push(cur->left); if(cur->right)q2.push(cur->right); } cur->next=NULL; } else{ while(!q2.empty()){ cur=q2.front(); q2.pop(); if(prev)prev->next=cur; prev=cur; //把下层节点保存到q1 if(cur->left)q1.push(cur->left); if(cur->right)q1.push(cur->right); } cur->next=NULL; } } } };
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