Week6 513. Find Bottom Left Tree Value

题目

Given a binary tree, find the leftmost value in the last row of the tree.

Example 1:

Input:    2   / \  1   3Output:1

Example 2: 

Input:        1       / \      2   3     /   / \    4   5   6       /      7Output:7

Note: You may assume the tree (i.e., the given root node) is not NULL.

分析

其实这个问题其实只要从右往左做BFS就特别简单，最下层的最左值即为最后一次从队列中出来的节点的值。

代码

class Solution {public:    int findBottomLeftValue(TreeNode* root) {        queue<TreeNode*> q;        q.push(root);        auto temp = root;        while (!q.empty()) {            temp = q.front();            q.pop();            if (temp->right) q.push(temp->right);            if (temp->left) q.push(temp->left);        }        return temp->val;    }};