leetcode 日经贴，Cpp code -Populating Next Right Pointers in Each Node

Populating Next Right Pointers in Each Node

/**
 * 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 con(TreeLinkNode *r) {
        if (r->left && r->right) {
            r->left->next = r->right;
            r->right->next = NULL;
        } else {
            return;
        }
        if (r->next) {
            r->right->next = r->next->left;
        }
        con(r->left);
        con(r->right);
    }
    void connect(TreeLinkNode *root) {
        if(!root) {
            return ;
        }
        root->next = NULL;
        con(root);
    }
};