leetcode 1171.从链表中删去总和值为零的连续节点

⭐️ 题目描述

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leetcode链接：从链表中删去总和值为零的连续节点

思路： 在链表的 head 前新增加一个哨兵卫的头结点，方便计算前缀和。遍历链表，依次把每个节点的 val 相加到 sum 中去，再判断 sum = 0 依次删除这段区间的节点，要画图注意边界，以及迭代的条件即可。

代码：

struct ListNode* removeZeroSumSublists(struct ListNode* head){
    // 在链表前面加一个哨兵卫结点
    struct ListNode* newNode = (struct ListNode*)malloc(sizeof(struct ListNode));
    newNode->next = head;

    struct ListNode* cur = newNode;
    while (cur != NULL) {
        int sum = 0;
        struct ListNode* curNext = cur->next;
        // 前缀和
        while (curNext != NULL) {
            sum += curNext->val;
            // 当 sum = 0 时
            if (sum == 0) {
                // 释放 [cur->next , curNext]
                struct ListNode* temp = cur->next;
                while (temp != curNext) {
                    struct ListNode* next = temp->next;
                    free(temp);
                    temp = next;
                }
                cur->next = curNext->next;
                curNext = cur;
                free(temp);
            }
            curNext = curNext->next;
        }
        cur = cur->next;
    }

    head = newNode->next;
    free(newNode);
    return head;
}

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