Populating Next Right Pointers in Each Node II
/**
* 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 update(TreeLinkNode *cur, TreeLinkNode *p) {
p = p->next;
while (p) {
if (p->left) {
cur->next = p->left;
cur = cur->next;
}
if (p->right) {
cur->next = p->right;
cur = cur->next;
}
p = p->next;
}
cur->next = NULL;
}
void con(TreeLinkNode *r) {
if (!r) return;
TreeLinkNode *c = r->right? r->right:r->left;
if (r->left && r->right) {
r->left->next = r->right;
}
if (c && !c->next) {
update(c, r);
}
con(r->left);
con(r->right);
}
void connect(TreeLinkNode *root) {
if (!root) return;
root->next = NULL;
con(root);
}
};