leetcode513找树左下角的值(JAVA实现）

实际上也是广度优先搜索，不过有了一点改变，先右在左，等于镜像的广度优先遍历

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    
    public int findBottomLeftValue(TreeNode root) {
        LinkedList ll = new LinkedList();
        ll.offer(root);
        while (!ll.isEmpty()) {
            root = ll.poll();
            if (root.right != null) ll.offer(root.right);//先右在左，相当与镜像的右边第一个
            if (root.left != null) ll.offer(root.left);
        }
        return root.val;
    }
    
}