116. Populating Next Right Pointers in Each Node
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
注意這題的需求
1. use only extra constant space ----> cann't use resursive. use iterative to do the recursive work
2.perfect binary tree --> each nonleaf node has two child
這題基本上就是一個node做好兩件事情，
1. 把自己的 left child next 跟 right child 接好
2.如果自己有next，就把right child next 也跟 自己的next.left接好
然後一層一層做就可以了
