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程式語言 - LeetCode - C++ - 572. Subtree of Another Tree

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題目：


解答：

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    bool is_same(TreeNode *a, TreeNode *b) {
        if (!a && !b) {
            return true;
        }

        if (!a || !b) {
            return false;
        }

        if (a->val != b->val) {
            return false;
        }

        return is_same(a->left, b ->left) && is_same(a->right, b->right); 
    }

    bool isSubtree(TreeNode* root, TreeNode* subRoot) {
        if (!root) {
            return false;
        }

        if (is_same(root, subRoot)) {
            return true;
        }

        return isSubtree(root->left, subRoot) || isSubtree(root->right, subRoot);
    }
};