a times b

#include<bits/stdc++.h>
using namespace std;

string multiply(string num1, string num2)
{
    int len1 = num1.size();
    int len2 = num2.size();
    if (len1 == 0 || len2 == 0)
    return "0";

    vector<int> result(len1 + len2, 0);

    int i_n1 = 0; 
    int i_n2 = 0; 

    for (int i=len1-1; i>=0; i--)
    {
        int carry = 0;
        int n1 = num1[i] - '0';

        i_n2 = 0; 
           
        for (int j=len2-1; j>=0; j--)
        {
            int n2 = num2[j] - '0';

            int sum = n1*n2 + result[i_n1 + i_n2] + carry;

            carry = sum/10;

            result[i_n1 + i_n2] = sum % 10;

            i_n2++;
        }

        if (carry > 0)
            result[i_n1 + i_n2] += carry;

        i_n1++;
    }

    int i = result.size() - 1;
    while (i>=0 && result[i] == 0)
    i--;

    if (i == -1)
    return "0";

    string s = "";
    
    while (i >= 0)
        s += std::to_string(result[i--]);

    return s;
}

int main()
{
    string a, b;
    cin >> a >> b;

    cout << multiply(a, b);
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: ACCEPTED

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: ACCEPTED

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: ACCEPTED

Test 31

Verdict: ACCEPTED

Test 32

Verdict: ACCEPTED

Test 33

Verdict: ACCEPTED

Test 34

Verdict: ACCEPTED

Test 35

Verdict: ACCEPTED

Test 36

Verdict: ACCEPTED

Test 37

Verdict: ACCEPTED

Test 38

Verdict: ACCEPTED

Test 39

Verdict: ACCEPTED

Test 40

Verdict: ACCEPTED

Test 41

Verdict: ACCEPTED

Test 42

Verdict: ACCEPTED

Test 43

Verdict: ACCEPTED

Test 44

Verdict: ACCEPTED

Test 45

Verdict: ACCEPTED

Test 46

Verdict: ACCEPTED

Test 47

Verdict: ACCEPTED

Test 48

Verdict: ACCEPTED

Test 49

Verdict: ACCEPTED

Test 50

Verdict: ACCEPTED

Test 51

Verdict: ACCEPTED

Test 52

Verdict: ACCEPTED

Test 53

Verdict: ACCEPTED

Test 54

Verdict: ACCEPTED

Test 55

Verdict: ACCEPTED

Test 56

Verdict: TIME LIMIT EXCEEDED

Test 57

Verdict: TIME LIMIT EXCEEDED

Test 58

Verdict: TIME LIMIT EXCEEDED

Test 59

Verdict: TIME LIMIT EXCEEDED

Test 60

Verdict: TIME LIMIT EXCEEDED