feat: update solutions to lc problem: No.0019

No.0019.Remove Nth Node From End of List

Author: yanglbme

solution/0000-0099/0013.Roman to Integer/Solution.py

@@ -1,7 +1,6 @@
 class Solution:
     def romanToInt(self, s: str) -> int:
-        romans = {'I': 1, 'V': 5, 'X': 10,
-                  'L': 50, 'C': 100, 'D': 500, 'M': 1000}
+        romans = {'I': 1, 'V': 5, 'X': 10, 'L': 50, 'C': 100, 'D': 500, 'M': 1000}
         ans = 0
         for i in range(len(s) - 1):
             if romans[s[i]] < romans[s[i + 1]]:

solution/0000-0099/0019.Remove Nth Node From End of List/README.md

@@ -50,7 +50,13 @@
 
 <!-- 这里可写通用的实现逻辑 -->
 
-利用快慢指针。
+**方法一：快慢指针**
+
+定义两个指针 `fast` 和 `slow`，初始时都指向链表的虚拟头结点 `dummy`。
+
+接着 `fast` 指针先向前移动 $n$ 步，然后 `fast` 和 `slow` 指针同时向前移动，直到 `fast` 指针到达链表的末尾。此时 `slow.next` 指针指向的结点就是倒数第 `n` 个结点的前驱结点，将其删除即可。
+
+时间复杂度 $O(n)$，空间复杂度 $O(1)$。其中 $n$ 为链表的长度。
 
 <!-- tabs:start -->
 
@@ -65,7 +71,7 @@
 #         self.val = val
 #         self.next = next
 class Solution:
-    def removeNthFromEnd(self, head: ListNode, n: int) -> ListNode:
+    def removeNthFromEnd(self, head: Optional[ListNode], n: int) -> Optional[ListNode]:
         dummy = ListNode(next=head)
         fast = slow = dummy
         for _ in range(n):
@@ -151,19 +157,16 @@ public:
  * }
  */
 func removeNthFromEnd(head *ListNode, n int) *ListNode {
-    dummy := &ListNode{0, head}
-    fast := dummy
-    slow := dummy
-    for n > 0 {
-        fast = fast.Next
-        n -= 1
-    }
-    for fast.Next != nil {
-        slow = slow.Next
-        fast = fast.Next
-    }
-    slow.Next = slow.Next.Next
-    return dummy.Next
+	dummy := &ListNode{0, head}
+	fast, slow := dummy, dummy
+	for ; n > 0; n-- {
+		fast = fast.Next
+	}
+	for fast.Next != nil {
+		slow, fast = slow.Next, fast.Next
+	}
+	slow.Next = slow.Next.Next
+	return dummy.Next
 }
 ```
 
@@ -265,6 +268,37 @@ impl Solution {
 }
 ```
 
+### **TypeScript**
+
+```ts
+/**
+ * Definition for singly-linked list.
+ * class ListNode {
+ *     val: number
+ *     next: ListNode | null
+ *     constructor(val?: number, next?: ListNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.next = (next===undefined ? null : next)
+ *     }
+ * }
+ */
+
+function removeNthFromEnd(head: ListNode | null, n: number): ListNode | null {
+    const dummy = new ListNode(0, head);
+    let fast = dummy;
+    let slow = dummy;
+    while (n--) {
+        fast = fast.next;
+    }
+    while (fast.next) {
+        slow = slow.next;
+        fast = fast.next;
+    }
+    slow.next = slow.next.next;
+    return dummy.next;
+}
+```
+
 ### **...**
 
 ```

solution/0000-0099/0019.Remove Nth Node From End of List/README_EN.md

@@ -54,7 +54,7 @@
 #         self.val = val
 #         self.next = next
 class Solution:
-    def removeNthFromEnd(self, head: ListNode, n: int) -> ListNode:
+    def removeNthFromEnd(self, head: Optional[ListNode], n: int) -> Optional[ListNode]:
         dummy = ListNode(next=head)
         fast = slow = dummy
         for _ in range(n):
@@ -138,19 +138,16 @@ public:
  * }
  */
 func removeNthFromEnd(head *ListNode, n int) *ListNode {
-    dummy := &ListNode{0, head}
-    fast := dummy
-    slow := dummy
-    for n > 0 {
-        fast = fast.Next
-        n -= 1
-    }
-    for fast.Next != nil {
-        slow = slow.Next
-        fast = fast.Next
-    }
-    slow.Next = slow.Next.Next
-    return dummy.Next
+	dummy := &ListNode{0, head}
+	fast, slow := dummy, dummy
+	for ; n > 0; n-- {
+		fast = fast.Next
+	}
+	for fast.Next != nil {
+		slow, fast = slow.Next, fast.Next
+	}
+	slow.Next = slow.Next.Next
+	return dummy.Next
 }
 ```
 
@@ -252,6 +249,37 @@ impl Solution {
 }
 ```
 
+### **TypeScript**
+
+```ts
+/**
+ * Definition for singly-linked list.
+ * class ListNode {
+ *     val: number
+ *     next: ListNode | null
+ *     constructor(val?: number, next?: ListNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.next = (next===undefined ? null : next)
+ *     }
+ * }
+ */
+
+function removeNthFromEnd(head: ListNode | null, n: number): ListNode | null {
+    const dummy = new ListNode(0, head);
+    let fast = dummy;
+    let slow = dummy;
+    while (n--) {
+        fast = fast.next;
+    }
+    while (fast.next) {
+        slow = slow.next;
+        fast = fast.next;
+    }
+    slow.next = slow.next.next;
+    return dummy.next;
+}
+```
+
 ### **...**
 
 ```

solution/0000-0099/0019.Remove Nth Node From End of List/Solution.go

@@ -5,18 +5,15 @@
  *     Next *ListNode
  * }
  */
- func removeNthFromEnd(head *ListNode, n int) *ListNode {
-    dummy := &ListNode{0, head}
-    fast := dummy
-    slow := dummy
-    for n > 0 {
-        fast = fast.Next
-        n -= 1
-    }
-    for fast.Next != nil {
-        slow = slow.Next
-        fast = fast.Next
-    }
-    slow.Next = slow.Next.Next
-    return dummy.Next
+func removeNthFromEnd(head *ListNode, n int) *ListNode {
+	dummy := &ListNode{0, head}
+	fast, slow := dummy, dummy
+	for ; n > 0; n-- {
+		fast = fast.Next
+	}
+	for fast.Next != nil {
+		slow, fast = slow.Next, fast.Next
+	}
+	slow.Next = slow.Next.Next
+	return dummy.Next
 }

solution/0000-0099/0019.Remove Nth Node From End of List/Solution.py

@@ -4,7 +4,7 @@
 #         self.val = val
 #         self.next = next
 class Solution:
-    def removeNthFromEnd(self, head: ListNode, n: int) -> ListNode:
+    def removeNthFromEnd(self, head: Optional[ListNode], n: int) -> Optional[ListNode]:
         dummy = ListNode(next=head)
         fast = slow = dummy
         for _ in range(n):

solution/0000-0099/0019.Remove Nth Node From End of List/Solution.ts

@@ -0,0 +1,26 @@
+/**
+ * Definition for singly-linked list.
+ * class ListNode {
+ *     val: number
+ *     next: ListNode | null
+ *     constructor(val?: number, next?: ListNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.next = (next===undefined ? null : next)
+ *     }
+ * }
+ */
+
+function removeNthFromEnd(head: ListNode | null, n: number): ListNode | null {
+    const dummy = new ListNode(0, head);
+    let fast = dummy;
+    let slow = dummy;
+    while (n--) {
+        fast = fast.next;
+    }
+    while (fast.next) {
+        slow = slow.next;
+        fast = fast.next;
+    }
+    slow.next = slow.next.next;
+    return dummy.next;
+}

solution/0000-0099/0028.Find the Index of the First Occurrence in a String/Solution.py

@@ -1,7 +1,7 @@
 class Solution:
     def strStr(self, haystack: str, needle: str) -> int:
         n, m = len(haystack), len(needle)
-        for i in range(n-m+1):
-            if haystack[i:i+m] == needle:
+        for i in range(n - m + 1):
+            if haystack[i : i + m] == needle:
                 return i
         return -1

solution/CONTEST_README.md

@@ -11,8 +11,8 @@
 
 | 段位  | 比例   | 段位名   | 国服分数线    | 勋章                                                                    |
 | ----- | ------ | -------- | --------- | --------------------------------------------------------------------------- |
-| LV3 | 5%  | Guardian | &ge;2234.22 | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Guardian.gif" style="width: 80px;" /></p> |
-| LV2 | 20% | Knight   | &ge;1875.44 | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Knight.gif" style="width: 80px;" /></p>   |
+| LV3 | 5%  | Guardian | &ge;2235.51 | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Guardian.gif" style="width: 80px;" /></p> |
+| LV2 | 20% | Knight   | &ge;1875.65 | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Knight.gif" style="width: 80px;" /></p>   |
 | LV1 | 75% | -        | -         | -                                                                           |
 
 力扣竞赛 **全国排名前 10** 的用户，全站用户名展示为品牌橙色。

solution/CONTEST_README_EN.md

@@ -13,8 +13,8 @@ If you are in the top 25% of the contest rating, you’ll get the “Knight” b
 
 | Level | Proportion | Badge      | Rating |                                                                                                                         |
 | ----- | ---------- | ---------- | -------------- | ----------------------------------------------------------------------------------------------------------------------- |
-| LV3 | 5\%      | Guardian | &ge;2184.20   | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Guardian.gif" style="width: 80px;" /></p> |
-| LV2 | 20\%     | Knight   | &ge;1849.64   | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Knight.gif" style="width: 80px;" /></p>   |
+| LV3 | 5\%      | Guardian | &ge;2177.33   | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Guardian.gif" style="width: 80px;" /></p> |
+| LV2 | 20\%     | Knight   | &ge;1850.13   | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Knight.gif" style="width: 80px;" /></p>   |
 | LV1 | 75\%     | -          | -              | -                                                                                                                       |
 
 For top 10 users (excluding LCCN users), your LeetCode ID will be colored orange on the ranking board. You'll also have the honor with you when you post/comment under discuss.

solution/contest.py

@@ -127,8 +127,8 @@ def generate_contest_list():
 
 | 段位  | 比例   | 段位名   | 国服分数线    | 勋章                                                                    |
 | ----- | ------ | -------- | --------- | --------------------------------------------------------------------------- |
-| LV3 | 5%  | Guardian | &ge;2234.22 | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Guardian.gif" style="width: 80px;" /></p> |
-| LV2 | 20% | Knight   | &ge;1875.44 | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Knight.gif" style="width: 80px;" /></p>   |
+| LV3 | 5%  | Guardian | &ge;2235.51 | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Guardian.gif" style="width: 80px;" /></p> |
+| LV2 | 20% | Knight   | &ge;1875.65 | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Knight.gif" style="width: 80px;" /></p>   |
 | LV1 | 75% | -        | -         | -                                                                           |
 
 力扣竞赛 **全国排名前 10** 的用户，全站用户名展示为品牌橙色。
@@ -154,8 +154,8 @@ def generate_contest_list():
 
 | Level | Proportion | Badge      | Rating |                                                                                                                         |
 | ----- | ---------- | ---------- | -------------- | ----------------------------------------------------------------------------------------------------------------------- |
-| LV3 | 5\%      | Guardian | &ge;2184.20   | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Guardian.gif" style="width: 80px;" /></p> |
-| LV2 | 20\%     | Knight   | &ge;1849.64   | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Knight.gif" style="width: 80px;" /></p>   |
+| LV3 | 5\%      | Guardian | &ge;2177.33   | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Guardian.gif" style="width: 80px;" /></p> |
+| LV2 | 20\%     | Knight   | &ge;1850.13   | <p><img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/images/Knight.gif" style="width: 80px;" /></p>   |
 | LV1 | 75\%     | -          | -              | -                                                                                                                       |
 
 For top 10 users (excluding LCCN users), your LeetCode ID will be colored orange on the ranking board. You'll also have the honor with you when you post/comment under discuss.