CONY的世界

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

Given a nested list of integers, implement an iterator to flatten it.

Each element is either an integer, or a list -- whose elements may also be integers or other lists.

Example 1:

Given the list [[1,1],2,[1,1]],

By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,1,2,1,1].

Example 2:

Given the list [1,[4,[6]]],

By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,4,6].

這一題要注意的地方是 NestedInteger 要在 hasNext() 裡面展開，而不是在next()

因為如果展開後沒有integer 要return false

ex.[ [ ] ] 的測資

如果是在next 裡面展開就會錯誤，因為實際上根本沒有可以return的 integer