Algorithm
Problem Name: 83. Remove Duplicates from Sorted List
Given the head of a sorted linked list, delete all duplicates such that each element appears only once. Return the linked list sorted as well.
Example 1:
Input: head = [1,1,2] Output: [1,2]
Example 2:
Input: head = [1,1,2,3,3] Output: [1,2,3]
Constraints:
- The number of nodes in the list is in the range
[0, 300]. -100 <= Node.val <= 100- The list is guaranteed to be sorted in ascending order.
Code Examples
#1 Code Example with C Programming
Code -
C Programming
struct ListNode* deleteDuplicates(struct ListNode* head) {
struct ListNode *prev, *p;
if (!head) return NULL;
prev = head;
p = prev->next;
while (p) {
if (prev->val != p->val) {
prev->next = p;
prev = p;
p = p->next;
}
prev->next = NULL;
return head;
}
Input
Output
#2 Code Example with C++ Programming
Code -
C++ Programming
// Recursive
class Solution {
public:
ListNode* deleteDuplicates(ListNode* head) {
if(!head || !head->next) return head;
auto p = deleteDuplicates(head->next);
head->next = p;
return p->val == head->val ? p : head;
}
};
// Non-recursive
class Solution {
public:
ListNode* deleteDuplicates(ListNode* head) {
if(!head || !head->next) return head;
ListNode* pre = head, *cur = head->next;
while(cur){
pre->val == cur->val ? pre->next = cur->next : pre = cur;
cur = cur->next;
}
return head;
}
};
Input
Output
#3 Code Example with Java Programming
Code -
Java Programming
class Solution {
public ListNode deleteDuplicates(ListNode head) {
ListNode curr = head;
while (curr != null) {
while (curr.next != null && curr.next.val == curr.val) {
curr.next = curr.next.next;
}
curr = curr.next;
}
return head;
}
}
Input
Output
#4 Code Example with Javascript Programming
Code -
Javascript Programming
const deleteDuplicates = function(head) {
let current = head;
while (current !== null && current.next !== null) {
if (current.val === current.next.val) {
current.next = current.next.next;
} else {
current = current.next;
}
}
return head;
};
Input
Output
#5 Code Example with Python Programming
Code -
Python Programming
class Solution:
def deleteDuplicates(self, head):
cur = root = head
while head:
if head.val != cur.val:
cur.next = cur = head
head = cur.next = head.next
return root
Input
Output
#6 Code Example with C# Programming
Code -
C# Programming
namespace LeetCode
{
public class _083_RemoveDuplicatesFromSortedList
{
public ListNode DeleteDuplicates(ListNode head)
{
if (head == null) { return null; }
var p = head;
while (p.next != null)
{
if (p.val == p.next.val)
p.next = p.next.next;
else
p = p.next;
}
return head;
}
}
}
Input
Output