[面试真题] LeetCode：Same Tree

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.

广度优先遍历，考察两棵树中每一个的值以及左右孩子的值是否相等。

Program Runtime: 8 milli secs

/**
 * Definition for binary tree
 * 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) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        if(q == p){
            return true;
        }
        queue<TreeNode*> qq, qp;
        if(NULL == p && NULL == q){
            return true;
        }else if(NULL != p && NULL != q){
            qq.push(q);
            qp.push(p);
        }else{
            return false;
        }
        while(qq.size() != 0 && qp.size() != 0){
            TreeNode *curp = qp.front();
            qp.pop();
            TreeNode *curq = qq.front();
            qq.pop();
            if(curq->val != curp->val){
                return false;
            }
            if(curp->left && curq->left) {
                if(curp->left->val != curq->left->val){
                    return false;
                }
                qp.push(curp->left);
                qq.push(curq->left);
            }else if(curp->left != NULL && curq->left == NULL){
                return false;
            }else if(curp->left == NULL && curq->left != NULL){
                return false;
            }
            if(curp->right && curq->right) {
                if(curp->right->val != curq->right->val){
                    return false;
                }
                qp.push(curp->right);
                qq.push(curq->right);
            }else if(curp->right != NULL && curq->right == NULL){
                return false;
            }else if(curp->right == NULL && curq->right != NULL){
                return false;
            }
        }
        if(qq.size() != 0 || qp.size() != 0){
            return false;
        }
        return true;
    }
};