Same Tree

1. Question

给定两个二叉树，判断是不是相同（结构相同，值相同）的树。

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.

2. Solution

考虑特殊情况：

• 树为空：都为空，某个为空

采用分支法解决：

• 顶点相同
• 左子树相同
• 右子树相同

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