Leetcode - [Medium]2. Add Two Numbers

leetcode.com/problems/add-two-numbers/

Add Two Numbers - LeetCode

 

Solution

 

#include <stdio.h>
#include <malloc.h>
 
struct ListNode {
    int val;
    struct ListNode* next;
};
 
struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2) {
    int sum, carry = 0, val1, val2, num;
    struct ListNode* rst_node = 0;
    struct ListNode* last_node = 0;
 
    while (1) {
        if (l1 != 0) {
            val1 = l1->val;
            l1 = l1->next;
        }
        else {
            val1 = 0;
        }
 
        if (l2 != 0) {
            val2 = l2->val;
            l2 = l2->next;
        }
        else {
            val2 = 0;
        }
 
        sum = val1 + val2 + carry;
        carry = sum / 10 == 1 ? 1 : 0;
        num = sum % 10;
 
        struct ListNode* new_node = (struct ListNode*)malloc(sizeof(struct ListNode));
        new_node->val = num;
        new_node->next = 0;
        if (rst_node == 0) {
            rst_node = new_node;
        }
        else {
            last_node->next = new_node;
        }
        last_node = new_node;
 
        if (l1 == 0 && l2 == 0 && carry == 0) break;
    }    
 
    return rst_node;
}
 
struct ListNode* a = 0;
struct ListNode* b = 0;
 
void add_a(int value) {
    struct ListNode* new_node = (struct ListNode*)malloc(sizeof(struct ListNode));
    new_node->val = value;
    new_node->next = a;
    a = new_node;
}
 
void add_b(int value) {
    struct ListNode* new_node = (struct ListNode*)malloc(sizeof(struct ListNode));
    new_node->val = value;
    new_node->next = b;
    b = new_node;
}
 
int main() {
 
    add_a(2);
    add_a(4);
    add_a(3);
 
    add_b(5);
    add_b(6);
    add_b(4);
 
    struct ListNode* node = addTwoNumbers(a, b);
    while (node) {
        printf("%d ", node->val);
        node = node->next;
    }
    puts("");
 
    return 0;
}