【LeetCode】513. Find Bottom Left Tree Value

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

Example 1:

Input:

    2
   / \
  1   3

Output:
1

Example 2: 

Input:

        1
       / \
      2   3
     /   / \
    4   5   6
       /
      7

Output:
7

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

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var findBottomLeftValue = function(root) {
    var res=new Array();
    var queue=new Array();
    var bottomLeft;
    queue.push(root);
    while(queue.length>0){
        
        var temp=new Array();
        while(queue.length>0){
            var n=queue.shift();
            bottomLeft=n.val;
             if(n.right!=null){
                temp.push(n.right);
            }if(n.left!=null){
                temp.push(n.left);
                
            }
        }
        queue=temp;
    }
    return bottomLeft;
}; 

一道BFS题目，思路就是用一个队列，遍历每层。