Populating Next Right Pointers in Each Node
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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
思路:
递归和非递归的思路差不多,简单说下递归吧:
根节点的位置比较特殊,不需要往右边链接的,但是到了下面,就要判断一下额外的条件了,一个是自身右边的链接是否打通还有一个就是自身是否有右节点,没有直接返回,有的话就是自身右节点孩子的next 指向自身 next 的左孩子。
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 ; if(root->left&&root->right){ root->left->next=root->right; } if(root->next&&root->left){//到了非根节点的时候 root->right->next=root->next->left; } connect(root->left);connect(root->right); }*/ void connect(TreeLinkNode *root){ if(root==NULL) return ; while(root&&root->left){ TreeLinkNode *tmp=root->left; while(root){ root->left->next=root->right; if(root->next){ root->right->next=root->next->left; } root=root->next; } root=tmp; } }};
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- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
- Populating Next Right Pointers in Each Node
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