WEI-CHENG CHEN

解法

class Solution {
public:
    TreeNode* sortedListToBST(ListNode* head) {
        if (!head) return nullptr;
        if (!head->next) return new TreeNode(head->val);

        // STEP01：要先找到中間
        ListNode* prev = nullptr;
        ListNode* slow = head;
        ListNode* fast = head;
        while(fast && fast->next){
            prev = slow;
            slow = slow->next;
            fast = fast->next->next;
        }
        prev->next = nullptr; // 切掉左半段

        // STEP02 建子點
        ListNode* mid = slow;
        TreeNode* root = new TreeNode(mid->val);
        root->left = sortedListToBST(head);
        root->right = sortedListToBST(mid->next);
        return root;
    }
};