872. Leaf-Similar Trees*

872. Leaf-Similar Trees*

https://leetcode.com/problems/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.

C++ 实现 1

前序遍历; 将叶子节点 (左右节点均为空) 加入到数组中, 最后进行数组的比较.

/**
 * 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 {
public:
    bool leafSimilar(TreeNode* root1, TreeNode* root2) {
        vector<int> v1, v2;
        dfs(root1, v1);
        dfs(root2, v2);
        return v1 == v2;
    }
private:
    void dfs(TreeNode *root, vector<int> &res) {
        if (!root) return;
        if (!root->left && !root->right) res.push_back(root->val);
        dfs(root->left, res);
        dfs(root->right, res);
    }
};