Airwrk - coding test

PROBLEM1.cpp

#include <bits/stdc++.h>
#define debug(x) printf("-----------------%d\n", x);
#define LEN sizeof(a) / sizeof(a[0])
#define MEM(arr, k) memset(arr, k, sizeof arr)
#define input freopen("01input.txt", "r", stdin)
#define output freopen("01output.txt", "w", stdout)
#define go                            \
    ios_base::sync_with_stdio(false); \
    cin.tie(0);                       \
    cout.tie(0);
using namespace std;
int X8[] = {0, 1, 0, -1, 1, -1, 1, -1};
int Y8[] = {1, 0, -1, 0, 1, -1, -1, 1};
int X4[] = {1, -1, 0, 0};
int Y4[] = {0, 0, 1, -1};

vector<int> runningsum(int nums[], int len){ 
    int ans[len];
    ans[0] = nums[0];
    for (int i = 1; i < len; i++)
    { 
        ans[i] = ans[i-1] + nums[i];
    }
    
    //putting ans array in vector as the example said to return vector
    vector<int> ans_vec;
    for (int i = 0; i < len; i++)
    {
        ans_vec.push_back(ans[i]);
    }
    return ans_vec;
}

int main()
{
    int num[] = {1, 2, 3, 4};
    int len = sizeof(num) / sizeof(num[0]);
}

PROBLEM2.cpp

#include<bits/stdc++.h>
#define debug(x) printf("-----------------%d\n",x);
#define LEN sizeof(a)/sizeof(a[0])
#define MEM(arr,k) memset(arr,k,sizeof arr)
#define input freopen("01input.txt","r",stdin)
#define output freopen("01output.txt","w",stdout)
#define go ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
using namespace std;
int X8[] = {0, 1, 0, -1, 1, -1, 1, -1};
int Y8[] = {1, 0, -1, 0, 1, -1, -1, 1};
int X4[] = {1, -1, 0, 0};
int Y4[] = {0, 0 , 1, -1};


bool solve(int n)
{
    string s = to_string(n);
    string copy_of_s = s;
    reverse(copy_of_s.begin(), copy_of_s.end());
    //if reversed string starts with zero, it won't be possible to get back the original string
    if(copy_of_s[0]=='0')
        return false;
    return true;
}

int main(){
    if(solve(123))
        cout << "true";
    else
        cout << "false"; 
}

PROBLEM3.cpp

#include<bits/stdc++.h>
#define debug(x) printf("-----------------%d\n",x);
#define LEN sizeof(a)/sizeof(a[0])
#define MEM(arr,k) memset(arr,k,sizeof arr)
#define input freopen("01input.txt","r",stdin)
#define output freopen("01output.txt","w",stdout)
#define go ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
using namespace std;
int X8[] = {0, 1, 0, -1, 1, -1, 1, -1};
int Y8[] = {1, 0, -1, 0, 1, -1, -1, 1};
int X4[] = {1, -1, 0, 0};
int Y4[] = {0, 0 , 1, -1};

int sumofdigit(int n)
{
    int sum = 0;
    //taking the last digit, adding it to sum then dividing n by 10 to mod the next digit
    while(n>0){
        sum += n % 10;
        n = n / 10;
    }
    return sum;
}

int solve(int n)
{
    while(n>9)
    {
        n = sumofdigit(n);
    }
    return n;
}

int main(){
    cout << solve(38);
}