BM15 删除有序链表中重复的元素-I

https://www.nowcoder.com/practice/c087914fae584da886a0091e877f2c79

标准解法

func deleteDuplicates( head *ListNode ) *ListNode {
    if head == nil { // 注意边界条件的判断
        return head
    }
    o := head
    for head.Next != nil {
        if head.Val == head.Next.Val {
            head.Next = head.Next.Next
        } else {
            head = head.Next
        }
    }    
    return o
}

23/5/10 暴力解法

用时 8分钟

func deleteDuplicates(head *ListNode) *ListNode {
    m := make(map[int]struct{})
    dummy := new(ListNode)
    pre := dummy
    for head != nil {
        if _, ok := m[head.Val]; !ok {
            m[head.Val] = struct{}{}
            pre.Next = &ListNode{Val: head.Val}
            pre = pre.Next
        }
        head = head.Next
    }
    return dummy.Next
}

暴力解法非常简单，使用 map 来记录已经出现过的值，如果出现过就不再添加，否则就添加到链表中