LeetCode100 鐩稿悓鐨勬爲

Posted 2021-01-25

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濡傛灉涓や釜鏍戝湪缁撴瀯涓婄浉鍚岋紝骞朵笖鑺傜偣鍏锋湁鐩稿悓鐨勫€硷紝鍒欒涓哄畠浠槸鐩稿悓鐨勩€?/p>

绀轰緥 1:

杈撳叆:       1         1
          /        /          2   3     2   3

        [1,2,3],   [1,2,3]

杈撳嚭: true

绀轰緥 2:

杈撳叆:      1          1
          /                    2             2

        [1,2],     [1,null,2]

杈撳嚭: false

绀轰緥 3:

杈撳叆:       1         1
          /        /          2   1     1   2

        [1,2,1],   [1,1,2]

杈撳嚭: false

---

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
/*
绠楁硶鎬濇兂锛?
    閲囩敤閫掑綊锛岄€掑綊姣旇緝涓ゆ５鏍戝嵆鍙€?
*/
class Solution {
public:
    bool isSameTree(TreeNode* p, TreeNode* q) {
        if(!p && !q)
            return true;
        if((!p&&q)||(p&&!q)||(p->val!=q->val))
            return false;
        return isSameTree(p->left,q->left)&&isSameTree(p->right,q->right);
    }
};
/*
绠楁硶鎬濇兂锛?
    閲囩敤杩唬锛屽埄鐢ㄦ爤淇濆瓨缁撶偣鐒跺悗姣旇緝缁撶偣鍗冲彲銆?
*/
class Solution {
public:
    bool isSameTree(TreeNode* p, TreeNode* q) {
        stack<TreeNode*> s1, s2;
        if (p)  s1.push(p);
        if (q)  s2.push(q);
        while (!s1.empty() && !s2.empty()) {
            TreeNode *t1 = s1.top(); s1.pop();  //杩欐槸鍏抽敭锛屽厛鍙栧湪寮规爤
            TreeNode *t2 = s2.top(); s2.pop();
            if (t1->val != t2->val) 
                return false;
            
            if (t1->left) s1.push(t1->left);
            if (t2->left) s2.push(t2->left);
            if (s1.size() != s2.size()) 
                return false;
            
            if (t1->right) s1.push(t1->right);
            if (t2->right) s2.push(t2->right);
            if (s1.size() != s2.size()) 
                return false;
        }
        return s1.size() == s2.size();
    }
};