Same Tree

Was I saying that Max Depth of Binary tree is the easiest? I was wrong.

Problem: 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.


/**
 * Definition for binary tree
 * 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;
        //After this two lines, the only case that left is p != null && q != null
        
        if (p.val == q.val) return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
        else return false;
    }
}
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