leetcode_c++:树:Populating Next Right Pointers in Each Node II(117)

Follow up for problem “Populating Next Right Pointers in Each Node”.

What if the given tree could be any binary tree? Would your previous solution still work?

Note:

You may only use constant extra space.
For example,
Given the following binary tree,

        1        /  \      2    3     / \    \    4   5    7

After calling your function, the tree should look like:

        1 -> NULL       /  \      2 -> 3 -> NULL     / \    \    4-> 5 -> 7 -> NULL

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class Solution {public:    void connect(TreeLinkNode *root) {        TreeLinkNode header(0);        header.next = root;        TreeLinkNode *cur, *prev;        while (header.next) {            // current header's link is already populated            // following will make a new children-link to header            cur = header.next;            prev = &header;            header.next = nullptr;            for (; cur; cur = cur->next) {                if (cur->left != nullptr) {                    prev->next = cur->left;                    prev = prev->next;                }                if (cur->right != nullptr) {                    prev->next = cur->right;                    prev = prev->next;                }            }        }    }};