LeetCode: 872. Leaf-Similar Trees

题目描述

Consider all the leaves of a binary tree. From left to right order, the values of those leaves form a leaf value sequence.

For example, in the given tree above, the leaf value sequence is (6, 7, 4, 9, 8).
Two binary trees are considered leaf-similar if their leaf value sequence is the same.
Return true if and only if the two given trees with head nodes root1 and root2 are leaf-similar.

Note:

Both of the given trees will have between 1 and 100 nodes.

题目大意：求给定两个树的叶子节点从左到右构成的序列是否相等。

解题思路

分别中序遍历两棵树，按顺序记录各自的叶子，然后比较是否相等。

AC 代码

/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */
class Solution {
    void getLeaves(TreeNode* root, list<int>& leaves)
    {
        if(root == nullptr) return ;
        if(root->left == nullptr && root->right == nullptr)
        {
            leaves.push_back(root->val);
            return;
        }

        getLeaves(root->left, leaves);
        getLeaves(root->right, leaves);
    }
public:
    bool leafSimilar(TreeNode* root1, TreeNode* root2) {
        list<int> leaves1, leaves2;

        getLeaves(root1, leaves1);
        getLeaves(root2, leaves2);

        return (leaves1 == leaves2);
    }
};