Fork me on GitHub

Find Bottom Left Tree Value

Posted on

Description

https://leetcode.com/problems/find-bottom-left-tree-value/description/

Solution

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
/**
 * 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:
    int findBottomLeftValue(TreeNode* root) {
        map<int, int> depthMapping;
        int depth = 0;
        helper(root, depthMapping, depth);
        return depthMapping.rbegin()->second;
    }
    
    void helper(TreeNode* root, map<int, int>& depthMapping, int depth) {
        if (root == NULL) return;
        helper(root->left, depthMapping, depth + 1);
        auto iter = depthMapping.find(depth);
        if(iter == depthMapping.end()) depthMapping[depth] = root->val;
        helper(root->right, depthMapping, depth + 1);
        return;
    }
};