剑指 Offer 26. 树的子结构

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */

bool isSubStructure2(struct TreeNode* A, struct TreeNode* B) {
    if (B == NULL) 
        return true;
    if (A == NULL)
        return false;
    if (A->val != B->val)
        return false;
    return isSubStructure2(A->left, B->left) && isSubStructure2(A->right, B->right);
 }

bool isSubStructure(struct TreeNode* A, struct TreeNode* B){
    bool result =false;
    if (A && B) {
        if (A->val == B->val) {
            result = isSubStructure2(A, B);
        }
        if (result == false) {
            result = isSubStructure(A->left, B);
        }
        if (result == false) 
            result = isSubStructure(A->right, B);
    }
    return result;
}