gistfile1.txt

#include <iostream>
#include <map>

using namespace std;
#define MILLION 1000000

uint64_t collatz_func( uint64_t num )
{
    if (num % 2 == 0) {
        return num / 2 ;
    } else {
        return ( num * 3 ) + 1;
    }
}

uint64_t collatz_seq( uint64_t n ) {
    if ( n == 1) {
        return 0;
    } else {
        return  1 + collatz_seq(  collatz_func( n ) ) ;
    }
}


int main()
{

    uint64_t maxlen = 0;
    uint64_t maxidx =0;
    for (int i = 1 ; i < MILLION ; ++i ) {
        uint64_t len = collatz_seq( i ) ;
        if (len > maxlen) { maxlen = len; maxidx = i; }
    }
    std::cout << "i=" << maxidx << " len=" << maxlen << endl;
    return 0;
}