Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Plus One Linked List in C++
Suppose we have a non-negative integer represented as non-empty a singly linked list of digits, now we have to plus one to the integer. We may assume the integer do not contain any leading zero, except the number 0 itself. In the linked list the most significant digit is at the head of the list.
So, if the input is like [1,2,3], then the output will be [1,2,4]
To solve this, we will follow these steps −
if head is null, then −
return head
curr = head
req = NULL
while curr is non-zero, do −
if val of curr is not equal to 9, then −
req := curr
curr := next of curr
if not req is non-zero, then −
dummy = new node with value 1
next of dummy := head
while head is non-zero, do −
val of head := 0
head := next of head
return dummy
Otherwise
increase val of req by 1
req := next of req
while req is non-zero, do −
val of req := 0
req := next of req
return head
Example
Let us see the following implementation to get a better understanding.
#include <bits/stdc++.h>
using namespace std;
class ListNode{
public:
int val;
ListNode *next;
ListNode(int data){
val = data;
next = NULL;
}
};
ListNode *make_list(vector<int< v){
ListNode *head = new ListNode(v[0]);
for(int i = 1; i<v.size(); i++){
ListNode *ptr = head;
while(ptr->next != NULL){
ptr = ptr->next;
}
ptr->next = new ListNode(v[i]);
}
return head;
}
void print_list(ListNode *head){
ListNode *ptr = head;
cout << "[";
while(ptr){
cout << ptr->val << ", ";
ptr = ptr->next;
}
cout << "]" << endl;
}
class Solution {
public:
ListNode* plusOne(ListNode* head) {
if (!head)
return head;
ListNode* curr = head;
ListNode* req = NULL;
while (curr) {
if (curr->val != 9) {
req = curr;
}
curr = curr->next;
}
if (!req) {
ListNode* dummy = new ListNode(1);
dummy->next = head;
while (head) {
head->val = 0;
head = head->next;
}
return dummy;
}
else {
req->val++;
req = req->next;
while (req) {
req->val = 0;
req = req->next;
}
return head;
}
}
};
main(){
Solution ob;
vector<int< v = {1,4,5};
ListNode *head = make_list(v);
print_list(ob.plusOne(head));
}Input
{1,4,5}Output
[1, 4, 6, ]
133 Views
