コラッツ予想(競技プログラミング　総集編２０１３　２．１)

callatz.cc

#include <iostream>
using namespace std;

int solve(int n);

int main(void){
	while(true){
		int n; cin >> n;
		if(!n)
			break;
		
		cout << solve(n) << endl;
	}
	
	return 0;
}

int solve(int n){
	int count = 0;
	while(n != 1){
		if(n % 2 == 0)
			n = n / 2;
		else
			n = n * 3 + 1;
		++count;
	}
	
	return count;
}

input.txt

2
3
2398
2385
10000
0

run.bat

cmd /k "g++ callatz.cc & a.exe < input.txt"