1123.java

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 * int val;
 * TreeNode left;
 * TreeNode right;
 * TreeNode() {}
 * TreeNode(int val) { this.val = val; }
 * TreeNode(int val, TreeNode left, TreeNode right) {
 * this.val = val;
 * this.left = left;
 * this.right = right;
 * }
 * }
 */
class Solution {
    private TreeNode ans;
    private int maxDepth = -1;

    public TreeNode lcaDeepestLeaves(TreeNode root) {
        dfs(root,0);
        return ans;
    }

    private int dfs(TreeNode node,int depth){
        if(node==null){
            maxDepth = Math.max(maxDepth,depth);
            return depth;
        }
        int leftMaxDepth = dfs(node.left,depth+1); //获取左子树最深节点的深度
        int rightMaxDepth = dfs(node.right,depth+1); //获取右子树最深节点的深度
        if(leftMaxDepth==rightMaxDepth&&leftMaxDepth==maxDepth)
            ans = node;
        return Math.max(leftMaxDepth,rightMaxDepth);
    }
}