Lintcode469-Same Tree-Easy

469. Same 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

Example 1:

Input:{1,2,2,4},{1,2,2,4}
Output:true
Explanation:
       1             1
       /            / 
      2   2   and   2   2
     /             /
    4             4

are identical.

Example 2:

Input:{1,2,3,4},{1,2,3,#,4}
Output:false
Explanation:

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

are not identical.

 

 

注意：

return a.val == b.val... 不要写成return a == b ....!!!

递归法代码：

/**
 * 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: the root of binary tree a.
     * @param b: the root of binary tree b.
     * @return: true if they are identical, or false.
     */
    public boolean isIdentical(TreeNode a, TreeNode b) {
        if (a == null && b == null) {
            return true;
        }
        else if (a != null && b !=null) {
            return a.val == b.val 
                    && isIdentical(a.left, b.left) 
                    && isIdentical(a.right, b.right);
        } 
        else {
            return false;
        }
    }
}