[Swift]LeetCode1171. 从链表中删去总和值为零的连续节点 | Remove Zero Sum Consecutive Nodes from Linked List

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Given the head of a linked list, we repeatedly delete consecutive sequences of nodes that sum to 0 until there are no such sequences.

After doing so, return the head of the final linked list.  You may return any such answer.

 

(Note that in the examples below, all sequences are serializations of ListNode objects.)

Example 1:

Input: head = [1,2,-3,3,1]
Output: [3,1]
Note: The answer [1,2,1] would also be accepted.

Example 2:

Input: head = [1,2,3,-3,4]
Output: [1,2,4]

Example 3:

Input: head = [1,2,3,-3,-2]
Output: [1]

 

Constraints:

• The given linked list will contain between 1 and 1000 nodes.
• Each node in the linked list has -1000 <= node.val <= 1000.

---

给你一个链表的头节点 head，请你编写代码，反复删去链表中由 总和 值为 0 的连续节点组成的序列，直到不存在这样的序列为止。

删除完毕后，请你返回最终结果链表的头节点。

 

你能够返回任何知足题目要求的答案。

（注意，下面示例中的全部序列，都是对 ListNode 对象序列化的表示。）

示例 1：

输入：head = [1,2,-3,3,1]
输出：[3,1]
提示：答案 [1,2,1] 也是正确的。

示例 2：

输入：head = [1,2,3,-3,4]
输出：[1,2,4]

示例 3：

输入：head = [1,2,3,-3,-2]
输出：[1]

 

提示：

• 给你的链表中可能有 1 到 1000 个节点。
• 对于链表中的每一个节点，节点的值：-1000 <= node.val <= 1000.

---

Runtime: 28 ms

Memory Usage: 21.5 MB

 1 /**
 2  * Definition for singly-linked list.
 3  * public class ListNode {
 4  *     public var val: Int
 5  *     public var next: ListNode?
 6  *     public init(_ val: Int) {
 7  *         self.val = val
 8  *         self.next = nil
 9  *     }
10  * }
11  */
12 class Solution {
13     func removeZeroSumSublists(_ head: ListNode?) -> ListNode? {
14         var head = head
15         if head == nil {return head}
16         var sums:[Int:ListNode] = [Int:ListNode]()
17         var sum:Int = 0
18         var curr:ListNode? = head
19         while(curr != nil)
20         {
21             sum += curr!.val
22             if sum == 0
23             {
24                 head = curr?.next
25             }
26             if sums[sum] != nil
27             {
28                 sums[sum]!.next = curr?.next
29             }
30             else
31             {
32                 sums[sum] = curr
33             }
34             curr = curr?.next
35         }
36         return head        
37     }
38 }

---

36ms

 

 1 /**
 2  * Definition for singly-linked list.
 3  * public class ListNode {
 4  *     public var val: Int
 5  *     public var next: ListNode?
 6  *     public init(_ val: Int) {
 7  *         self.val = val
 8  *         self.next = nil
 9  *     }
10  * }
11  */
12 class Solution {
13     func removeZeroSumSublists(_ head: ListNode?) -> ListNode? {
14                
15         var arr = [Int]()
16         var sumArr = [Int]()
17         var dic = [0: -1]
18         var head = head
19         var invaildRange = [(Int, Int)]()
20         var i = 0
21         while head != nil {
22             if head!.val == 0 {
23                 head = head!.next
24                 continue
25             }
26             arr.append(head!.val)
27             if sumArr.count == 0 {
28                 sumArr.append(head!.val)
29             } else {
30                 sumArr.append(sumArr[sumArr.count-1]+head!.val)
31             }
32             if dic[sumArr[sumArr.count-1]] != nil {
33                 let lasti = dic[sumArr[sumArr.count-1]]!
34                 invaildRange.append((lasti+1, i))
35                 for j in lasti..<i {
36                     dic[sumArr[j+1]] = nil
37                 } 
38                 dic[sumArr[sumArr.count-1]] = lasti
39             } else {
40                 dic[sumArr[sumArr.count-1]] = i
41             }
42             head = head!.next
43             i += 1
44         }
45         if sumArr.count == 0 || sumArr[sumArr.count-1] == 0 {
46             return nil
47         }
48 
49         // print(invaildRange)
50         
51         var hd: ListNode? = nil
52         var res: ListNode? = nil
53 
54         invaildRange.append((Int.max, Int.max))
55         invaildRange.sort {
56             if $0.0 < $1.0 || ($0.0 == $1.0 && $0.1 > $1.1 ) {
57                 return true
58             }
59             return false
60         }
61         var last = invaildRange.removeFirst()
62         for i in arr.indices {
63             while i > last.1 && invaildRange.count > 0 {
64                 last = invaildRange.removeFirst()
65             }
66             // print(i, last)
67             if i < last.0 {
68                 if hd == nil {
69                     hd = ListNode(arr[i])
70                     res = hd
71                 } else {
72                     hd!.next = ListNode(arr[i])
73                     hd = hd!.next
74                 }
75             }
76         }
77         return res 
78     }
79 }

---

44ms

 1 /**
 2  * Definition for singly-linked list.
 3  * public class ListNode {
 4  *     public var val: Int
 5  *     public var next: ListNode?
 6  *     public init(_ val: Int) {
 7  *         self.val = val
 8  *         self.next = nil
 9  *     }
10  * }
11  */
12 class Solution {
13     func removeZeroSumSublists(_ head: ListNode?) -> ListNode? { 
14         var arr = [Int](), sumArr = [Int]()
15         var dic = [0: -1]
16         var head = head
17         var invaildRange = [(Int, Int)]()
18         var i = 0
19         while head != nil {
20             //ignor zero element
21             if head!.val == 0 { head = head!.next; continue }
22             
23             arr.append(head!.val)
24             if sumArr.count == 0 { sumArr.append(head!.val) } 
25             else { sumArr.append(sumArr.last! + head!.val) }
26             
27             let lasti = dic[sumArr.last!] ?? i
28             if lasti != i {
29                 invaildRange.append((lasti+1, i))
30                 for j in lasti..<i {
31                     dic[sumArr[j+1]] = nil
32                 } 
33             } 
34             dic[sumArr.last!] = lasti
35             head = head!.next
36             i += 1
37         }
38         if sumArr.count == 0 || sumArr[sumArr.count-1] == 0 { return nil }
39         var hd: ListNode? = nil
40         var res: ListNode? = nil
41 
42         invaildRange.append((Int.max, Int.max))
43         invaildRange.sort { $0.0 < $1.0  }
44         var last = invaildRange.removeFirst()
45         for i in arr.indices {
46             while i > last.1 { last = invaildRange.removeFirst() }
47             if i < last.0 {
48                 if hd == nil {
49                     hd = ListNode(arr[i])
50                     res = hd
51                 } else {
52                     hd!.next = ListNode(arr[i])
53                     hd = hd!.next
54                 }
55             }
56         }
57         return res 
58     }
59 }