In this post, we are going to solve the 83. Remove Duplicates from Sorted List problem of Leetcode. This problem 83. Remove Duplicates from Sorted List is a Leetcode easy level problem. Let’s see code, 83. Remove Duplicates from Sorted List – Leetcode Solution.

Problem

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.

Now, let’s see the code of 83. Remove Duplicates from Sorted List – Leetcode Solution.

Remove Duplicates from Sorted List – Leetcode Solution

83. Remove Duplicates from Sorted List – Solution in Java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
public class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        ListNode list = head;
         
         while(list != null) {
        	 if (list.next == null) {
        		 break;
        	 }
        	 if (list.val == list.next.val) {
        		 list.next = list.next.next;
        	 } else {
        		 list = list.next;
        	 }
         }
         
         return head;
    }
}

83. Remove Duplicates from Sorted List – Solution in C++

/**
 * 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* deleteDuplicates(ListNode* head) {
        ListNode* curr = head;
        while(curr!=NULL and curr->next!=NULL){
            if(curr->val==curr->next->val){
                ListNode* temp = curr->next;
                curr->next = curr->next->next;
                delete(temp);
            }
            else curr=curr->next;
        }
        return head;
    }
};

83. Remove Duplicates from Sorted List – Solution in Python

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution(object):
    def deleteDuplicates(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        cur = head
        while cur:
            while cur.next and cur.next.val == cur.val:
                cur.next = cur.next.next     # skip duplicated node
            cur = cur.next     # not duplicate of current node, move to next node
        return head

Note: This problem 83. Remove Duplicates from Sorted List is generated by Leetcode but the solution is provided by CodingBroz. This tutorial is only for Educational and Learning purpose.