669. 修剪二叉搜索树c

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
struct TreeNode* trimBST(struct TreeNode* root, int low, int high) {
    if(!root) return NULL;
    if(root->val>=low && root->val<=high){
        root->left=trimBST(root->left,low,high);
        root->right=trimBST(root->right,low,high);
    }else{
        if(root->val < low){
            return trimBST(root->right,low,high);
        }else if(root->val > high){
            return trimBST(root->left,low,high);
        }
    }
    return root;
}

结果：