gcd in c 2b 2b

1#include<iostream>
2using namespace std;
3long long gcd(long long a, long long b) 
4{ 
5    if (b == 0) 
6        return a; 
7    return gcd(b, a % b);  
8      
9} 
10int main()
11{
12	long long a,b;
13	cin>>a>>b;
14	cout<<gcd(a,b);
15}

1int gcd(int a, int b) 
2{ 
3    // Everything divides 0  
4    if (a == 0) 
5       return b; 
6    if (b == 0) 
7       return a; 
8    // base case 
9    if (a == b) 
10        return a; 
11    // a is greater 
12    if (a > b) 
13        return gcd(a-b, b); 
14    return gcd(a, b-a); 
15}

1#include<iostream>
2using namespace std;
3
4int euclid_gcd(int a, int b) {
5	if(a==0 || b==0) return 0;
6	int dividend = a;
7	int divisor = b;
8	while(divisor != 0){
9		int remainder = dividend%divisor;
10		dividend = divisor;
11		divisor = remainder;
12	}
13	return dividend;
14}
15
16int main()
17{
18	cout<<euclid_gcd(0,7)<<endl;
19	cout<<euclid_gcd(55,78)<<endl;
20	cout<<euclid_gcd(105,350)<<endl;
21	cout<<euclid_gcd(350,105)<<endl;
22	return 0;
23}

1cout << __gcd(17, 97) << endl; //#include <algorithm> 
2