给定一个表示整数的链表，其中每个节点是所表示整数的数字。任务是将给定的数字N添加到表示的整数中。
例子：
Input: LL = 9 -> 9 -> 3 -> NULL, N = 7
Output: 1 -> 0 -> 0 -> 0 -> NULL
993 + 7 = 1000
Input: LL = 2 -> 9 -> 9 -> NULL, N = 5
Output: 3 -> 0 -> 4 -> NULL
方法：这里讨论了解决此问题的迭代方法。在本文中，将讨论一种递归方法。
这个想法是递归地遍历LinkedList，直到到达最后一个节点。到达最后一个节点后，将N的值添加到它。添加后，如果该值大于9，则将进位和设置模式(数字％10)值保留为节点值，并将进位添加到先前的堆栈帧节点，并继续直到从堆栈中清除所有堆栈帧为止。
如果在清除了所有堆栈帧之后仍然有一个进位，则使用此值创建一个新节点，该节点将是链接列表的新头，指向前一个头。
下面是上述方法的实现：
C++
// C++ implementation of the approach
#include
using namespace std;
// Node class contains value
// and next node reference
struct ListNode
{
int value;
ListNode* next;
};
// To store the carry
int carry = 0;
void addNewValue(ListNode*, int);
// Function that calls the recursive method
// addNewValue to add a digit to the
// number represented as the linked list
ListNode* addValue(ListNode* head,
int addValue)
{
// Add the digit recursively
addNewValue(head, addValue);
// If there is a carry after the addition
if (carry != 0)
{
// Create a new node
ListNode* newHead = new ListNode();
// Assign it with carry
newHead->value = carry;
// Make it point to the head of
// the linked list
newHead->next = head;
carry = 0;
// Make it the new head
return newHead;
}
// If there's not carry then
// return the previous head
else
{
return head;
}
}
// Recursive function to add a digit to the number
// represented as the given linked list
void addNewValue(ListNode* head,
int addValue)
{
// If it is the last node in the list
if (head->next == NULL)
{
// Add the digit
int val = head->value + addValue;
// Find the carry if any
head->value = val % 10;
carry = val / 10;
}
else
{
// Preserve the current node's value and call
// the recursive function for the next node
int val = head->value;
addNewValue(head->next, addValue);
val = val + carry;
head->value = val % 10;
carry = val / 10;
}
}
// Utility function to print the linked list
void printList(ListNode* node)
{
while (node != NULL)
{
cout << node->value << " -> ";
node = node->next;
}
cout<<"NULL";
}
// Driver code
int main()
{
// Create the linked list 9 -> 9 -> 3 -> NULL
ListNode* head = new ListNode();
head->value = 9;
head->next = new ListNode();
head->next->value = 9;
head->next->next = new ListNode();
head->next->next->value = 3;
head->next->next->next = NULL;
// Digit to be added
int n = 7;
head = addValue(head, n);
printList(head);
}
// This code is contributed by rutvik_56 Java
// Java implementation of the approach
// Node class contains value
// and next node reference
class ListNode {
int value;
ListNode next;
}
class GFG {
// To store the carry
private static int carry = 0;
// Function that calls the recursive method
// addNewValue to add a digit to the
// number represented as the linked list
public static ListNode addValue(ListNode head, int addValue)
{
// Add the digit recursively
addNewValue(head, addValue);
// If there is a carry after the addition
if (carry != 0) {
// Create a new node
ListNode newHead = new ListNode();
// Assign it with carry
newHead.value = carry;
// Make it point to the head of
// the linked list
newHead.next = head;
carry = 0;
// Make it the new head
return newHead;
}
// If there's not carry then
// return the previous head
else {
return head;
}
}
// Recursive function to add a digit to the number
// represented as the given linked list
private static void addNewValue(ListNode head, int addValue)
{
// If it is the last node in the list
if (head.next == null) {
// Add the digit
int val = head.value + addValue;
// Find the carry if any
head.value = val % 10;
carry = val / 10;
}
else {
// Preserve the current node's value and call
// the recursive function for the next node
int val = head.value;
addNewValue(head.next, addValue);
val = val + carry;
head.value = val % 10;
carry = val / 10;
}
}
// Utility function to print the linked list
private static void printList(ListNode node)
{
while (node != null) {
System.out.print(node.value + " -> ");
node = node.next;
}
System.out.print("NULL");
}
// Driver code
public static void main(String[] args)
{
// Create the linked list 9 -> 9 -> 3 -> NULL
ListNode head = new ListNode();
head.value = 9;
head.next = new ListNode();
head.next.value = 9;
head.next.next = new ListNode();
head.next.next.value = 3;
head.next.next.next = null;
// Digit to be added
int n = 7;
head = addValue(head, n);
printList(head);
}
}Python
# Python implementation of the approach
# Node class contains value
# and next node reference
class ListNode:
def __init__(self, new_data):
self.value = new_data
self.next = None
# To store the carry
carry = 0
# Function that calls the recursive method
# addNewValue to add a digit to the
# number represented as the linked list
def addValue(head, addValue):
global carry
# Add the digit recursively
addNewValue(head, addValue)
# If there is a carry after the addition
if (carry != 0) :
# Create a node
newHead = ListNode(0)
# Assign it with carry
newHead.value = carry
# Make it point to the head of
# the linked list
newHead.next = head
carry = 0
# Make it the head
return newHead
# If there's not carry then
# return the previous head
else :
return head
# Recursive function to add a digit to the number
# represented as the given linked list
def addNewValue(head,addValue):
global carry
# If it is the last node in the list
if (head.next == None) :
# Add the digit
val = head.value + addValue
# Find the carry if any
head.value = val % 10
carry = int(val / 10)
else :
# Preserve the current node's value and call
# the recursive function for the next node
val = head.value
addNewValue(head.next, addValue)
val = val + carry
head.value = val % 10
carry = int(val / 10)
# Utility function to print the linked list
def printList(node):
while (node != None) :
print(node.value ,end= " -> ")
node = node.next
print("None")
# Driver code
# Create the linked list 9 -> 9 -> 3 -> None
head = ListNode(0)
head.value = 9
head.next = ListNode(0)
head.next.value = 9
head.next.next = ListNode(0)
head.next.next.value = 3
head.next.next.next = None
# Digit to be added
n = 7
head = addValue(head, n)
printList(head)
# This code is contributed by Arnab KunduC#
// C# implementation of the approach
using System;
// Node class contains value
// and next node reference
public class ListNode
{
public int value;
public ListNode next;
}
class GFG
{
// To store the carry
private static int carry = 0;
// Function that calls the recursive method
// addNewValue to add a digit to the
// number represented as the linked list
public static ListNode addValue(ListNode head,
int addValue)
{
// Add the digit recursively
addNewValue(head, addValue);
// If there is a carry after the addition
if (carry != 0)
{
// Create a new node
ListNode newHead = new ListNode();
// Assign it with carry
newHead.value = carry;
// Make it point to the head of
// the linked list
newHead.next = head;
carry = 0;
// Make it the new head
return newHead;
}
// If there's not carry then
// return the previous head
else
{
return head;
}
}
// Recursive function to add a digit to the number
// represented as the given linked list
private static void addNewValue(ListNode head,
int addValue)
{
// If it is the last node in the list
if (head.next == null)
{
// Add the digit
int val = head.value + addValue;
// Find the carry if any
head.value = val % 10;
carry = val / 10;
}
else
{
// Preserve the current node's value and call
// the recursive function for the next node
int val = head.value;
addNewValue(head.next, addValue);
val = val + carry;
head.value = val % 10;
carry = val / 10;
}
}
// Utility function to print the linked list
private static void printList(ListNode node)
{
while (node != null)
{
Console.Write(node.value + " -> ");
node = node.next;
}
Console.Write("NULL");
}
// Driver code
public static void Main(String[] args)
{
// Create the linked list 9 -> 9 -> 3 -> NULL
ListNode head = new ListNode();
head.value = 9;
head.next = new ListNode();
head.next.value = 9;
head.next.next = new ListNode();
head.next.next.value = 3;
head.next.next.next = null;
// Digit to be added
int n = 7;
head = addValue(head, n);
printList(head);
}
}
// This code is contributed by PrinciRaj1992输出：
1 -> 0 -> 0 -> 0 -> NULL