LeetCode 94. Binary Tree Inorder Traversal

Description

Given a binary tree, return the inorder traversal of its nodes’ values.
For example:
Given binary tree[1,null,2,3],

    1     \      2     /    3

return [1,3,2].

Solution

思路：题意为中序遍历二叉树。遍历顺序为左—>根—>右，考虑到用递归比较简单，本文使用递归的思想进行解决。

/** * Definition for binary tree * struct TreeNode {        int val;        TreeNode *left;        TreeNode *right;        TreeNode(int x): val(x), left(NULL), right(NULL) {} }; */class Solution {public:    void inOrderTraversal(vector<int>& vi,TreeNode* root)    {        if(root->left) inOrderTraversal(vi,root->left);        vi.push_back(root->val);        if(root->right) inOrderTraversal(vi,root->right);    }    vector<int> inorderTraversal(TreeNode* root) {        vector<int> vi;        if(!root) return vi;        inOrderTraversal(vi,root);        return vi;    }};