100. Same Tree Java Solutions

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.

 

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/**
 * 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) || (p != null && q == null) ) return false;
        return p.val==q.val && isSameTree(p.left,q.left) && isSameTree(p.right,q.right);
    }
    
}

递归重要的就是确定递归出口，第一次递归出口没有确定好，导致一直无法AC。