feat: update leetcode solutions: No.0019. Remove Nth Node From End of…

… List
doocs · Mar 28, 2021 · 692acff · 692acff
1 parent f69c63a
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diff --git a/solution/0000-0099/0019.Remove Nth Node From End of List/README.md b/solution/0000-0099/0019.Remove Nth Node From End of List/README.md
@@ -26,6 +26,8 @@
 
 <!-- 这里可写通用的实现逻辑 -->
 
+利用快慢指针。
+
 <!-- tabs:start -->
 
 ### **Python3**
@@ -40,13 +42,12 @@
 #         self.next = next
 class Solution:
     def removeNthFromEnd(self, head: ListNode, n: int) -> ListNode:
-        dummy = ListNode(0, head)
+        dummy = ListNode(next=head)
         p = q = dummy
         for i in range(n):
             p = p.next
-        while p.next is not None:
-            p = p.next
-            q = q.next
+        while p.next:
+            p, q = p.next, q.next
         q.next = q.next.next
         return dummy.next
 ```
@@ -83,6 +84,65 @@ class Solution {
 }
 ```
 
+### **C++**
+
+```cpp
+/**
+ * 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* removeNthFromEnd(ListNode* head, int n) {
+        ListNode* dummy = new ListNode(0, head);
+        ListNode* p = dummy;
+        ListNode* q = dummy;
+        while (n-- > 0) {
+            p = p->next;
+        }
+        while (p->next != nullptr) {
+            p = p->next;
+            q = q->next;
+        }
+        q->next = q->next->next;
+        return dummy->next;
+    }
+};
+```
+
+### **Go**
+
+```go
+/**
+ * Definition for singly-linked list.
+ * type ListNode struct {
+ *     Val int
+ *     Next *ListNode
+ * }
+ */
+func removeNthFromEnd(head *ListNode, n int) *ListNode {
+    dummy := &ListNode{Val:0, Next:head}
+    p := dummy
+    q := dummy
+    for n > 0 {
+        p = p.Next
+        n--
+    }
+    for p.Next != nil {
+        p = p.Next
+        q = q.Next
+    }
+    q.Next = q.Next.Next
+    return dummy.Next
+}
+```
+
 ### **...**
 
 ```

diff --git a/solution/0000-0099/0019.Remove Nth Node From End of List/README_EN.md b/solution/0000-0099/0019.Remove Nth Node From End of List/README_EN.md
@@ -40,13 +40,12 @@ After removing the second node from the end, the linked list becomes <strong>1-&
 #         self.next = next
 class Solution:
     def removeNthFromEnd(self, head: ListNode, n: int) -> ListNode:
-        dummy = ListNode(0, head)
+        dummy = ListNode(next=head)
         p = q = dummy
         for i in range(n):
             p = p.next
-        while p.next is not None:
-            p = p.next
-            q = q.next
+        while p.next:
+            p, q = p.next, q.next
         q.next = q.next.next
         return dummy.next
 ```
@@ -81,6 +80,65 @@ class Solution {
 }
 ```
 
+### **C++**
+
+```cpp
+/**
+ * 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* removeNthFromEnd(ListNode* head, int n) {
+        ListNode* dummy = new ListNode(0, head);
+        ListNode* p = dummy;
+        ListNode* q = dummy;
+        while (n-- > 0) {
+            p = p->next;
+        }
+        while (p->next != nullptr) {
+            p = p->next;
+            q = q->next;
+        }
+        q->next = q->next->next;
+        return dummy->next;
+    }
+};
+```
+
+### **Go**
+
+```go
+/**
+ * Definition for singly-linked list.
+ * type ListNode struct {
+ *     Val int
+ *     Next *ListNode
+ * }
+ */
+func removeNthFromEnd(head *ListNode, n int) *ListNode {
+    dummy := &ListNode{Val:0, Next:head}
+    p := dummy
+    q := dummy
+    for n > 0 {
+        p = p.Next
+        n--
+    }
+    for p.Next != nil {
+        p = p.Next
+        q = q.Next
+    }
+    q.Next = q.Next.Next
+    return dummy.Next
+}
+```
+
 ### **...**
 
 ```

diff --git a/solution/0000-0099/0019.Remove Nth Node From End of List/Solution.cpp b/solution/0000-0099/0019.Remove Nth Node From End of List/Solution.cpp
@@ -1,25 +1,27 @@
+/**
+ * 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* removeNthFromEnd(ListNode* head, int n) {
-        ListNode *p, *q ;
-        q = head ;
-        p = head ;
-
-        for (int i = 0; i < n; ++i)
-            q = q->next ;
-
-        if (!q)
-        {
-            return head->next ;
+        ListNode* dummy = new ListNode(0, head);
+        ListNode* p = dummy;
+        ListNode* q = dummy;
+        while (n-- > 0) {
+            p = p->next;
         }
-
-        while (q->next)
-        {
-            q = q->next ;
-            p = p->next ;
+        while (p->next != nullptr) {
+            p = p->next;
+            q = q->next;
         }
-
-        p->next = p->next->next ;
-        return head ;
+        q->next = q->next->next;
+        return dummy->next;
     }
 };
diff --git a/solution/0000-0099/0019.Remove Nth Node From End of List/Solution.go b/solution/0000-0099/0019.Remove Nth Node From End of List/Solution.go
@@ -6,18 +6,17 @@
  * }
  */
  func removeNthFromEnd(head *ListNode, n int) *ListNode {
-	node0 := &ListNode{Val:0}
-	node0.Next = head
-	left := node0
-	right := node0
-	for n>0 {
-		right = right.Next
-		n--
-	}	
-	for right.Next != nil {
-		left = left.Next
-		right = right.Next
-	}
-	left.Next = left.Next.Next
-    return node0.Next
+    dummy := &ListNode{Val:0, Next:head}
+    p := dummy
+    q := dummy
+    for n > 0 {
+        p = p.Next
+        n--
+    }
+    for p.Next != nil {
+        p = p.Next
+        q = q.Next
+    }
+    q.Next = q.Next.Next
+    return dummy.Next
 }
diff --git a/solution/0000-0099/0019.Remove Nth Node From End of List/Solution.py b/solution/0000-0099/0019.Remove Nth Node From End of List/Solution.py
@@ -5,12 +5,11 @@
 #         self.next = next
 class Solution:
     def removeNthFromEnd(self, head: ListNode, n: int) -> ListNode:
-        dummy = ListNode(0, head)
+        dummy = ListNode(next=head)
         p = q = dummy
         for i in range(n):
             p = p.next
-        while p.next is not None:
-            p = p.next
-            q = q.next
+        while p.next:
+            p, q = p.next, q.next
         q.next = q.next.next
-        return dummy.next
+        return dummy.next