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.
思路：如果两个树相同，那么他们的左子树、右子树必定也相同=>递归=>可用前序、中序或后续遍历。
以下用的是前序遍历，先处理根节点。
/** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */ class Solution { public: bool isSameTree(TreeNode* p, TreeNode* q) { if (p==NULL && q==NULL) return true; else if(p!=NULL && q!=NULL) { if(p->val != q->val) return false; } else return false; if (!isSameTree(p->left,q->left)) return false; if (!isSameTree(p->right,q->right)) return false; return true; } };
原文：http://www.cnblogs.com/qionglouyuyu/p/6063803.html