leetcode100. Same Tree

100. Same Tree

Given two binary trees, write a function to check if they are equal or not.

Two binary trees are considered equal if they are structurally identical and the nodes have the same value.

解法

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        if (p == null && q == null) {
            return true;
        }
        if (p == null || q == null) {
            return false;
        }
        if (p.val == q.val) {
            boolean left = isSameTree(p.left, q.left);
            boolean right = isSameTree(p.right, q.right);
            return (left && right);
        }
        return false;
    }
}

代码也可以直接写成

if (p.val == q.val) {
    return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
}

性能更好一点