116.填充每个节点的下一个右侧节点指针.cpp

/*
 * @lc app=leetcode.cn id=116 lang=cpp
 *
 * [116] 填充每个节点的下一个右侧节点指针
 */

// @lc code=start
/*
// Definition for a Node.
class Node {
public:
    int val;
    Node* left;
    Node* right;
    Node* next;

    Node() : val(0), left(NULL), right(NULL), next(NULL) {}

    Node(int _val) : val(_val), left(NULL), right(NULL), next(NULL) {}

    Node(int _val, Node* _left, Node* _right, Node* _next)
        : val(_val), left(_left), right(_right), next(_next) {}
};
*/

class Solution {
public:
    // 通过 next 实现按层遍历
    Node* connect(Node* root) {
        if (!root) return root;
        for (auto cur = root; cur->left; cur = cur->left) {
            for (auto p = cur; p; p = p->next) {
                p->left->next = p->right;
                if(p->next) p->right->next = p->next->left;
            }
        }
        return root;
    }
};
// @lc code=end