Algorithm

[LeetCode 2] Add Two Numbers [C] [Runtime : 32 MS]

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2017-04-20

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04/20

1. Description

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order and each of their nodes contain a single digit. Add the two numbers and return it as a linked list.

2. Example

You may assume the two numbers do not contain any leading zero, except the number 0 itself.
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8

3. Code

struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2)
{
    struct ListNode* mHead = (struct ListNode *)malloc(sizeof(struct ListNode));
    struct ListNode* mPreNode = mHead;
    int mCarry = 0, mSum = 0;

    while (l1 != NULL || l2 != NULL || mCarry != 0)
    {
        struct ListNode* mResult = (struct ListNode *)malloc(sizeof(struct ListNode));
        mSum = (l1 ? l1->val : 0) + (l2 ? l2->val : 0) + mCarry;
        mResult->val = (mSum) % 10;
        mCarry = mSum / 10;
        mPreNode = mPreNode->next = mResult;
        l1 = l1 ? l1->next : NULL;
        l2 = l2 ? l2->next : NULL;
    }
    mPreNode->next = NULL;
    return mHead->next;
}

struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2)
{
    struct ListNode* mPreNode = l1;
    struct ListNode* mHead = l1;
    int mCarry = 0, mSum = 0;

    while (l1 != NULL && (l2 != NULL || mCarry != 0))
    {
        mSum = l1->val + (l2 ? l2->val : 0) + mCarry;
        l1->val = mSum % 10;
        mCarry = mSum / 10;

        mPreNode = l1;
        l1 = l1 ? l1->next : NULL;
        l2 = l2 ? l2->next : NULL;
    }

    if (l1 == NULL && l2 != NULL) {
        mPreNode->next = l2;
        l1 = l2;
    }

    while (mCarry != 0) {
        if (l1 == NULL) {
            l1 = (struct ListNode*)malloc(sizeof(struct ListNode));
            l1->next = NULL;
            l1->val = mCarry;
            mPreNode->next = l1;
            mCarry = 0;
        }
        else{
            mSum = l1->val + mCarry;
            l1->val = mSum % 10;
            mCarry = mSum / 10;
            mPreNode = l1;
            l1 = l1->next;
        }
    }

    return mHead;
}

#include<stdio.h>

struct ListNode
{
    int val;
    struct ListNode *next;
};

struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2)
{
    /* Replace with other tabs code */
}

struct ListNode* ArrayToLink(int aArray[], int aLength)
{
    struct ListNode* aHead = (struct ListNode*)malloc(sizeof(struct ListNode));
    struct ListNode* mPreNode = aHead;

    for (int i = 0; i < aLength; i++)
    {
        struct ListNode* mNode = (struct ListNode*)malloc(sizeof(struct ListNode));
        mNode->val = aArray[i];
        mPreNode->next = mNode;
        mPreNode = mNode;
    }
    mPreNode->next = NULL;

    return aHead;
}

int main()
{
    int mA1[] = { 1 }, mA2[] = { 9,9 };

    struct ListNode* mL1 = ArrayToLink(mA1, 1);
    struct ListNode* mL2 = ArrayToLink(mA2, 2);

    struct ListNode* mResult = addTwoNumbers(mL1->next, mL2->next);

    if (mResult != NULL)
    {
        printf("%d", mResult->val);
        mResult = mResult->next;
    }

    while (mResult != NULL)
    {
        printf(" -> %d", mResult->val);
        mResult = mResult->next;
    }

    system("pause");
    return 1;
}