L100. Same Tree

Problem:

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

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

Example 1:

Input:     1         1
          / \       / \
         2   3     2   3

        [1,2,3],   [1,2,3]

Output: true

Example 2:

Input:     1         1
          /           \
         2             2

        [1,2],     [1,null,2]

Output: false

Solution:

public boolean isSame(TreeNode p, TreeNode q){
    if(p == null && q == null) return true;
    if(p == null || q == null) return false;
    if(p.val != q.val) return false;
    else return isSame(p.left, q.left) && isSame(p.right, q.right);
}