破解编程面试---链接的加法 （八种编程语言的实现）
我们有两个非空链表，它们代表两个非负整数。这些数字以相反的顺序存储，并且它们的每个节点都包含一个数字。将两个数字相加，然后将它们作为链接列表返回。
您可能会假设两个数字除了数字0本身以外都不包含任何前导零。
例：
输入：（2-> 4-> 3）+（5-> 6-> 4）
输出：7-> 0-> 8
说明：342 + 465 = 807。
思路：
链表节点数据结构中包含值和下一个节点。
两个链表相加要对每个对应元素进行加操作；
如果计算结果超过了10，需要移位到高位；
如果有链表为空了，需要用最后的移位值0或者1对单独的链表中剩余的元素进行加操作；
最后再检查移位值，如果不为零，则添加为新元素。
Javascript:
class ListNode {
constructor(val, next=null) {
this.val = val;
}
}
addTwoNumbers = (l1, l2)=> {
let newNode = null;
let head = null;
let overTen = 0;
while(l1 != null && l2 != null) {
let sum = l1.val + l2.val + overTen;
let v1 = sum % 10;
overTen = parseInt(sum / 10);
if (head == null) {
head = new ListNode(v1);
newNode = head;
}
else {
newNode.next = new ListNode(v1);
newNode = newNode.next;
}
l1 = l1.next;
l2 = l2.next;
}
let l = !l1? l2 : l1;
while(l) {
let sum = l.val + overTen;
let v1 = sum % 10;
overTen = parseInt(sum / 10);
newNode.next = new ListNode(v1);
newNode = newNode.next;
l = l.next;
}
if(overTen != 0) {
newNode.next = new ListNode(overTen);
}
return head;
};
{
let l1 = new ListNode(2);
l1.next = new ListNode(4);
l1.next.next = new ListNode(3);
let l2 = new ListNode(5);
l2.next = new ListNode(6);
l2.next.next = new ListNode(4);
let l = addTwoNumbers(l1, l2);
while(l != null) {
console.log(l.val);
l = l.next;
}
console.log();
}
{
let l1 = new ListNode(1);
l1.next = new ListNode(8);
let l2 = new ListNode(0);
let l = addTwoNumbers(l1, l2);
while(l != null) {
console.log(l.val);
l = l.next;
}
console.log();
}
Java:
import java.util.*;
public class HelloWorld{
static class ListNode {
int val;
ListNode next;
ListNode(int x) { val = x; }
}
public static ListNode addTwoNumbers(ListNode l1, ListNode l2) {
ListNode newNode = null;
ListNode head = null;
int overTen = 0;
while(l1 != null && l2 != null){
int sum = l1.val + l2.val + overTen;
int v1 = sum % 10;
overTen = sum / 10;
if(head == null){
head = new ListNode(v1);
newNode = head;
}
else{
newNode.next = new ListNode(v1);
newNode = newNode.next;
}
l1 = l1.next;
l2 = l2.next;
}
ListNode l = l1 == null? l2: l1;
while(l != null){
int sum = l.val + overTen;
int v1 = sum % 10;
overTen = sum / 10;
newNode.next = new ListNode(v1);
newNode = newNode.next;
l = l.next;
}
if(overTen != 0){
newNode.next = new ListNode(overTen);
}
return head;
}
public static void main(String []args){
{
ListNode l1 = new ListNode(2);
l1.next = new ListNode(4);
l1.next.next = new ListNode(3);
ListNode l2 = new ListNode(5);
l2.next = new ListNode(6);
l2.next.next = new ListNode(4);
ListNode l = addTwoNumbers(l1, l2);
while(l != null) {
System.out.print(l.val);
l = l.next;
}
System.out.println();
}
{
ListNode l1 = new ListNode(1);
l1.next = new ListNode(8);
ListNode l2 = new ListNode(0);
ListNode l = addTwoNumbers(l1, l2);
while(l != null) {
System.out.print(l.val);
l = l.next;
}
System.out.println();
}
}
}
C#:
using System;
class ListNode {
public int val;
public ListNode next;
public ListNode(int x) { val = x; }
}
class HelloWorld {
public static ListNode addTwoNumbers(ListNode l1, ListNode l2) {
ListNode newNode = null;
ListNode head = null;
int overTen = 0;
while(l1 != null && l2 != null){
int sum = l1.val + l2.val + overTen;
int v1 = sum % 10;
overTen = sum / 10;
if(head == null){
head = new ListNode(v1);
newNode = head;
}
else{
newNode.next = new ListNode(v1);
newNode = newNode.next;
}
l1 = l1.next;
l2 = l2.next;
}
ListNode l = l1 == null? l2: l1;
while(l != null){
int sum = l.val + overTen;
int v1 = sum % 10;
overTen = sum / 10;
newNode.next = new ListNode(v1);
newNode = newNode.next;
l = l.next;
}
if(overTen != 0){
newNode.next = new ListNode(overTen);
}
return head;
}
static void Main() {
Console.WriteLine("Hello World");
{
ListNode l1 = new ListNode(2);
l1.next = new ListNode(4);
l1.next.next = new ListNode(3);
ListNode l2 = new ListNode(5);
l2.next = new ListNode(6);
l2.next.next = new ListNode(4);
ListNode l = addTwoNumbers(l1, l2);
while(l != null) {
Console.Write(l.val);
l = l.next;
}
Console.WriteLine();
}
{
ListNode l1 = new ListNode(1);
l1.next = new ListNode(8);
ListNode l2 = new ListNode(0);
ListNode l = addTwoNumbers(l1, l2);
while(l != null) {
Console.Write(l.val);
l = l.next;
}
Console.WriteLine();
}
}
}
Swift:
import Foundation
public class ListNode {
public var val: Int
public var next: ListNode?
public init(_ val: Int) {
self.val = val
self.next = nil
}
}
func addTwoNumbers(_ la: ListNode?, _ lb: ListNode?) -> ListNode? {
var l1 = la
var l2 = lb
var newNode: ListNode?
var head: ListNode?
var overTen: Int = 0
while (l1 != nil && l2 != nil) {
var sum: Int = l1!.val + l2!.val + overTen
var v1 = sum % 10
overTen = sum / 10
if( head == nil) {
head = ListNode(v1)
newNode = head;
}
else {
newNode!.next = ListNode(v1)
newNode = newNode!.next
}
l1 = l1!.next
l2 = l2!.next
}
var l: ListNode? = l1 == nil ? l2 : l1
while (l != nil) {
var sum = l!.val + overTen
var v1 = sum % 10;
overTen = sum / 10;
newNode!.next = ListNode(v1);
newNode = newNode!.next;
l = l!.next;
}
if(overTen != 0) {
newNode!.next = ListNode(overTen)
}
return head
}
func test1() {
var l1: ListNode? = ListNode(2)
l1!.next = ListNode(4)
l1!.next!.next = ListNode(3)
var l2: ListNode? = ListNode(5)
l2!.next = ListNode(6)
l2!.next!.next = ListNode(4)
var l = addTwoNumbers(l1, l2)
while(l != nil) {
print("\(l!.val)", terminator:"")
l = l!.next
}
print("\n")
}
func test2() {
var l1: ListNode? = ListNode(1)
l1!.next = ListNode(8)
var l2: ListNode? = ListNode(0)
var l = addTwoNumbers(l1, l2)
while(l != nil) {
print("\(l!.val)", terminator:"")
l = l!.next
}
print("\n")
}
test1()
test2()
Kotlin:
import kotlin.properties.Delegates
class ListNode {
var `val`: Int = 0
var next: ListNode? = null
constructor(v: Int) {
this.`val` = v
}
}
fun addTwoNumbers(la: ListNode?, lb: ListNode?): ListNode? {
var l1: ListNode? = la
var l2: ListNode? = lb
var newNode: ListNode? = null
var head: ListNode? = null
var overTen: Int = 0
while (l1 != null && l2 != null) {
var sum: Int = l1?.`val` + l2?.`val` + overTen
var v1 = sum % 10
overTen = sum / 10
if (head == null) {
head = ListNode(v1)
newNode = head;
} else {
newNode?.next = ListNode(v1)
newNode = newNode?.next
}
l1 = l1?.next
l2 = l2?.next
}
var l: ListNode? = l1
if (l1 == null) {
l = l2
}
while (l != null) {
var sum = l?.`val` + overTen
var v1 = sum % 10;
overTen = sum / 10;
newNode?.next = ListNode(v1);
newNode = newNode?.next;
l = l?.next;
}
if (overTen != 0) {
newNode?.next = ListNode(overTen)
}
return head
}
fun main() {
test1()
test2()
}
private fun test1() {
var l1: ListNode? = ListNode(2)
l1?.next = ListNode(4)
l1?.next?.next = ListNode(3)
var l2: ListNode? = ListNode(5)
l2?.next = ListNode(6)
l2?.next?.next = ListNode(4)
var l = addTwoNumbers(l1, l2)
while (l != null) {
print("${l.`val`}")
l = l?.next
}
println()
}
private fun test2() {
var l1: ListNode? = ListNode(1)
l1?.next = ListNode(8)
var l2: ListNode? = ListNode(0)
var l = addTwoNumbers(l1, l2)
while (l != null) {
print("${l.`val`}")
l = l?.next
}
println()
}
Python:
class ListNode:
def __init__(self, x):
self.val = x
self.next = None
def addTwoNumbers(l1: ListNode, l2: ListNode) -> ListNode:
newNode = None
head = None
overTen = 0
while l1 != None and l2 != None:
sum = l1.val + l2.val + overTen
v1 = sum % 10
overTen = int(sum / 10)
if head == None:
head = ListNode(v1)
newNode = head
else:
newNode.next = ListNode(v1);
newNode = newNode.next
l1 = l1.next
l2 = l2.next
l = l1 if l1 != None else l2
while l != None:
v1 = l.val
if overTen != 0:
sum = l.val + overTen
v1 = sum % 10
overTen = int(sum / 10)
newNode.next = ListNode(v1);
newNode = newNode.next
l = l.next
if overTen != 0:
newNode.next = ListNode(overTen);
return head
def test1():
l1 = ListNode(2)
l1.next = ListNode(4)
l1.next.next = ListNode(3)
l2 = ListNode(5)
l2.next = ListNode(6)
l2.next.next = ListNode(4)
l = addTwoNumbers(l1, l2)
while l != None:
print(l.val, end = '')
l = l.next
print()
def test2():
l1 = ListNode(1)
l1.next = ListNode(8)
l2 = ListNode(0)
l = addTwoNumbers(l1, l2)
while l != None:
print(l.val, end = '')
l = l.next
print()
test1()
test2()
C++:
#include
#include
struct ListNode {
int val;
ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};
ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
ListNode *newNode = 0;
ListNode *head = 0;
int overTen = 0;
while(l1 != 0 && l2 != 0) {
int sum = l1->val + l2->val + overTen;
int v1 = sum % 10;
overTen = sum /10;
if(head == 0){
head = new ListNode(v1);
newNode = head;
}
else {
newNode->next = new ListNode(v1);
newNode = newNode->next;
}
delete l1;
delete l2;
l1 = l1->next;
l2 = l2->next;
}
ListNode* l = l1 != NULL ? l1: l2;
while(l != NULL) {
int v1 = l->val;
if(overTen != 0){
int sum = l->val + overTen;
v1 = sum % 10;
overTen = sum / 10;
}
newNode->next = new ListNode(v1);
newNode = newNode->next;
delete l;
l = l->next;
}
if(overTen != 0) {
newNode->next = new ListNode(overTen);
}
return head;
}
void test1 () {
ListNode *l1 = new ListNode(2);
l1->next = new ListNode(4);
l1->next->next = new ListNode(3);
ListNode *l2 = new ListNode(5);
l2->next = new ListNode(6);
l2->next->next = new ListNode(4);
ListNode *l = addTwoNumbers(l1, l2);
while(l != NULL) {
std::cout << l->val;
delete l;
l = l->next;
}
std::cout << std::endl;
}
void test2 () {
ListNode *l1 = new ListNode(1);
l1->next = new ListNode(8);
ListNode *l2 = new ListNode(0);
ListNode *l = addTwoNumbers(l1, l2);
while(l != NULL) {
std::cout << l->val;
delete l;
l = l->next;
}
std::cout << std::endl;
}
int main()
{
test1();
test2();
return 0;
}
Golang:
package main
import (
"fmt"
)
type ListNode struct {
Val int
Next *ListNode
}
func addTwoNumbers(l1 *ListNode, l2 *ListNode) *ListNode {
var newNode *ListNode = nil
var head *ListNode = nil
var overTen = 0
for l1 != nil && l2 != nil {
sum := l1.Val + l2.Val + overTen
v1 := sum % 10
overTen = sum /10
if head == nil {
head = &ListNode{Val: v1}
newNode = head
} else {
newNode.Next = &ListNode{Val: v1}
newNode = newNode.Next
}
l1 = l1.Next
l2 = l2.Next
}
l := l1
if l1 == nil {
l = l2
}
for l != nil {
v1 := l.Val;
if overTen != 0{
sum := l.Val + overTen
v1 = sum % 10
overTen = sum / 10
}
newNode.Next = &ListNode{Val: v1}
newNode = newNode.Next
l = l.Next
}
if overTen != 0 {
newNode.Next = &ListNode{Val: overTen }
}
return head
}
func test1() {
l1 := &ListNode {Val: 2}
l1.Next = &ListNode {Val: 4}
l1.Next.Next = &ListNode {Val: 3}
l2 := &ListNode {Val: 5}
l2.Next = &ListNode {Val: 6}
l2.Next.Next = &ListNode {Val: 4}
l := addTwoNumbers(l1, l2)
for l != nil {
fmt.Printf("%d", l.Val)
l = l.Next
}
fmt.Println();
}
func test2() {
l1 := &ListNode {Val: 1}
l1.Next = &ListNode {Val: 8}
l2 := &ListNode {Val: 0}
l := addTwoNumbers(l1, l2)
for l != nil {
fmt.Printf("%d", l.Val)
l = l.Next
}
fmt.Println();
}
func main() {
test1()
test2()
}
