[UVa] 100 – The 3n+1 Problem - http://kuoe0.ch/18/uva-100-the-3n-plus-1-problem/

The 3n + 1 Problem.cpp

#include <iostream>
#include <cstdio>
#include <cstdlib>
using namespace std;

long long int  MAX;

long long int count( int x ) {
	if ( x == 1 )
		return 0;
	return count( x == 1 ? 3 * x + 1 : ( x >> 1 ) ) + 1;
}

int main() {
	int a, b;
	while ( ~scanf( "%d %d", &a, &b ) ) {
		printf( "%d %d", a, b );
		if ( a > b )
			swap( a, b );
		MAX = 0;
		for ( int i = a; i < = b; ++i )
        		MAX = max( MAX, count( i ) + 1 );
		printf( " %lldn", MAX );
	}
	return 0;
}