Solution to Add Two Numbers by LeetCode

Question: http://oj.leetcode.com/problems/add-two-numbers/

Question Name: Add Two Numbers

# Definition for singly-linked list.

# class ListNode:

# def __init__(self, x):

# self.val = x

# self.next = None

class Solution:

# @return a ListNode

def addTwoNumbers(self, l1, l2):

return self._addTwoSingleNumbers(l1, l2, 0)

def _addTwoSingleNumbers(self, l1, l2, carry):

value = carry

# Make sure, either both l1 and l2 are None,

# or l2 is not None.

# To simplify the if-elif block

if l2 == None: l1, l2 = l2, l1

if l1 == None and l2 == None:

if value == 0: return None # No need to create a new node

else: return ListNode(value) # Create the last node

elif l1 == None:

# l2 is not None

value += l2.val

tempNode = ListNode(value % 10)

tempNode.next = self._addTwoSingleNumbers(None, l2.next, value/10)

return tempNode

else:

# Both are not None

value += l1.val + l2.val

tempNode = ListNode(value % 10)

tempNode.next = self._addTwoSingleNumbers(l1.next, l2.next, value/10)

return tempNode

3 Replies to “Solution to Add Two Numbers by LeetCode”

You don’t have much activity here recently…

#include <cassert>

/**

* Definition for singly-linked list.

* struct ListNode {

* int val;

* ListNode *next;

* ListNode(int x) : val(x), next(NULL) {}

* };

class Solution {

private:

int countList(ListNode *l)

{

assert(l != nullptr);

int len = 1;

while(l->next != nullptr)

l = l->next;

++len;

}

return len;

public:

ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {

if(l1 == nullptr || l2 == nullptr)return nullptr;

int carrying = 0, val = 0, addon = 0, len1 = countList(l1), len2 = countList(l2);

ListNode *newHead = nullptr, *l3 = nullptr, *itor = nullptr, *prev = nullptr;

if(len1 >= len2)

newHead = l1, l3 = l2;

else

newHead = l2, l3 = l1;

itor = newHead;

while(l3 != nullptr || itor != nullptr)

addon = (l3 == nullptr) ? 0 : l3->val;

val = itor->val + addon + carrying;

if(val >= 10)

itor->val = val % 10;

carrying = 1;

itor->val = val;

carrying = 0;

prev = itor;

itor = itor->next;

if(l3 != nullptr)

l3 = l3->next;

if(carrying == 1)

prev->next = new ListNode(1);

return newHead;

Sheng says:
June 7, 2016 at 8:43 pm
Yes. I am making the tool at rankinghistory.codesays.com. So I get less time to do these challenges.

def addNum(num1, num2):

str1 = ''

str2 = ''

n1 = num1[::-1]

n2 = num2[::-1]

for i1 in n1:

str1 += str(i1)

for i2 in n2:

str2 += str(i2)

return int(str1)+int(str2)

3 Replies to “Solution to Add Two Numbers by LeetCode”

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