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程式語言 - LeetCode - C++ - 86. Partition List

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題目：


解答：

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* partition(ListNode* head, int x) {
        ListNode d0;
        ListNode d1;
        ListNode *l = &d0;
        ListNode *r = &d1;

        while (head) {
            if (head->val < x) {
                l->next = head;
                l = l->next;
            }
            else {
                r->next = head;
                r = r->next;
            }

            head = head->next;
        }
        r->next = nullptr;
        l->next = d1.next;

        return d0.next;
    }
};