Leetcode - 相同的树

解题思路：(C#)
通过递归，前序遍历对比判断是否为相同的树。

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left;
 *     public TreeNode right;
 *     public TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
public bool IsSameTree(TreeNode p, TreeNode q)
        {
            //递归终止情况1：p, q都是null
            if (p == null && q == null)
            {
                return true;
            }
            //递归终止情况2：p, q中有一个为空，或者是p, q的节点值不等
            else if (p == null || q == null || p.val != q.val)
            {
                return false;
            }
            else
            {
                //递归看左子树是否相同
                bool isLeftSameTree = IsSameTree(p.left, q.left);
                //递归看右子树是否相同
                bool isRightSameTree = IsSameTree(p.right, q.right);
                return isLeftSameTree && isRightSameTree;
            }
        }
}