Project4

package recursion;

import java.util.Scanner;

public class Recursion {

// Class example
public static int sum_up(int n) {
	if (n <=0 ) {
		return 0;
	}
	else {
		return n + sum_up(n-1);
	}
}

// Class example
public static int sum_up_tail(int n) {
	return sum_up_tail(n, 0);
}
public static int sum_up_tail(int n, int tmp) {
	if (n <1 ) {
		return tmp;
	}
	else {
		return sum_up_tail(n-1, tmp+n);
	}
}

public static int fact(int n) {
	if(n==1) {
		return 1;
	} else {
		int result = n * fact(n-1);
		return result;
	}
}

public static int fib(int n) {
	if(n<=1) {
		return 1;
	} else {
		int result = fib(n-2)+fib(n-1);
		return result;
	}
}

public static int gcd(int num1, int num2) {
	if (num2<=num1 && num1%num2 == 0) {
		return num2;
	}else if(num1<num2) {
		return gcd(num2,num1);
	} else {
		return gcd(num2, num1%num2);
	}
}


public static int power (int x, int y) {
	if(y==0) {
		return 1;
	} else if (x==0) {
		return 0;
	} else if (y<0) {
        throw new IllegalArgumentException("Invalid Power");
	}   else {
		return x * power(x,y-1);
	}
}


public static int balance(int x, int y) {
	if(x-y==1) {
		return y; 
	} else if (y-x==1) {
		return x;
	} else if (x>y) {
		return balance(x-1,y+1);
	} else if (y>x) {
		return balance(x+1,y-1);
	}
	return x;
}
	
public static int Ackermann(int m, int n) {
	if(m==0) {
		return n+1;
	} else if(n==0) {
		return Ackermann(m-1,1);
	} else {
		return Ackermann(m-1,Ackermann(m,n-1));
	}
}

public static playGuessingGame(int m) {
	
}

}