Leetcode 117. Populating Next Right Pointers in Each Node II (Hard) (cpp)

Leetcode 117. Populating Next Right Pointers in Each Node II (Hard) (cpp)

Tag: Tree, Depth-first Search

Difficulty: Hard

/*117. Populating Next Right Pointers in Each Node II (Hard)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    7After calling your function, the tree should look like:1 -> NULL/  \2 -> 3 -> NULL/ \    \4-> 5 -> 7 -> NULL*//*** 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;}queue<TreeLinkNode*> q;q.push(root);while (!q.empty()) {int _size = q.size();for (int i = 0; i < _size; i++) {TreeLinkNode* node = q.front();q.pop();if (i < _size - 1) {node->next = q.front();}else {node->next = NULL;}if (node->left != NULL) {q.push(node->left);}if (node->right != NULL) {q.push(node->right);}}}}};