[Microsoft] Identical Binary Tree

Check if two binary trees are identical. Identical means the two binary trees have the same structure and every identical position has the same value.

Example

    1             1   / \           / \  2   2   and   2   2 /             /4             4

are identical.

    1             1   / \           / \  2   3   and   2   3 /               \4                 4

are not identical.

/** * Definition of TreeNode: * public class TreeNode { *     public int val; *     public TreeNode left, right; *     public TreeNode(int val) { *         this.val = val; *         this.left = this.right = null; *     } * } */public class Solution {    /**     * @param a, b, the root of binary trees.     * @return true if they are identical, or false.     */    public boolean isIdentical(TreeNode a, TreeNode b) {        if(a==null && b==null){            return true;        }        if(a==null ||  b==null){            return false;        }        if(a.val==b.val){            return isIdentical(a.left,  b.left) && isIdentical(a.right,  b.right);        }                return false;    }}