100 - The 3n + 1 problem

[jaredjohnson]

I'm just trying to get going on these online programming contest deals. At the programming-challenges.com website I get a restricted function error for the following code. on the Online-judge.uva.es I just get a wrong answer error.

Can anyone help me out here?


#include <iostream>
using namespace std;

int main()
{
int i, j;
long int count, max, num;


while(cin>>i>>j) {

max=0;
for(int k=i; k<j+1; k++) {
count=1;
num=k;
while(num!=1) {
if(num % 2 == 0)
num = num / 2;
else
num = 3 * num + 1;
count++;
}
if (count > max) max = count;
}
cout<<i<<" "<<j<<" "<<max<<endl;
}
}

[eleusive]

I'm not sure about the restricted function error, but you are getting WA because the first input is not necessarily less than the second.

[jaredjohnson]

I fixed it.

[mohiul alam prince]

Hi
why are u not solving this problem by using c/c++
this problem is easy for c/c++

MAP

[ImLazy]

I submit this code for problem #100. Not to solve the problem, but just a test.

Code: Select all

#include<stdio.h>
#include<alloc.h>
#include<string.h>
int main()
{
  char *p;
  char temp[1000];
  while(gets(temp)!=NULL)
  {
    p=malloc(strlen(temp)+1);
    strcpy(p,temp);
    puts(p);
    free(p);
  }
  return 0;
}

But get Compile Error. Why???

[UFP2161]

alloc.h is not part of the standard libraries.

[ImLazy]

So do you mean I can't use alloc.h for any problem? OK,I see.

[sumankar]

If I am not mistaken malloc() and the other similar fns are defined in stdlib.h.
Use it.

Regards,
Suman.

[carbing]

in the "The Input",it says:
The input will consist of a series of pairs of integers i and j...

what's the meaning of "a series of"?how can i know the number of the "pairs of integers i and j"?

is the number unsure?i don't know how to solve this with C++ if it is unsure.please help me,thank you.

[Eduard]

Hello carping.
If problem doesn't tell you when does input ends you must read while not end of file.
For C++ you can read for example in such way if you use iostream.

Code: Select all

While (cin >> a >> b)
{
// your solution //
}

or

Code: Select all

While (true) {
cin >> a >> b;
// Your solution //
}

Eduard

[carbing]

Thank you for your useful help.I think i have to learn more about the C++ language.Thanks again.

[jonaskoelker]

try running this:
time echo "1 1000000" | java Main
that is, take time on how long it takes to solve the biggest problem instance possible. I think you'll be surprised.

To speed it up, you might want to save some of your previous results, so you don't run through a gazillion iterations for each number. Btw, If ints don't overflow: use them; I think it's a safe bet to say that they're gonna be somewhat faster than longs -- assuming that the judges use a 32-bit machine (does kernel 2.4.x exist for 64-bitters?).

Anyways, best of luck,

Jonas.

[Insidetheasylum]

Well, I compiled the program on my computer using Dev-C++ (4.9.9.1), however, when I submit it, it return "compile error"

I'm not sure what I'm doing wrong below so that the "judge" doesn't like me =P

Code: Select all

#include <iostream>
using namespace std;

int main (int argc, char **argv){
    int maxcyclelength = 1;
    // Cycle through all values between argv[1] an argv[2]
    for(int min = atoi(argv[1]); min<atoi(argv[2]); min++){
            int currentlen = 1;
            int cnumber = min;
            // run the loop till the currentnumber is equal to 1
            while(cnumber != 1){
                                if( cnumber%2 != 0)
                                    cnumber = 3*cnumber+1;
                                    else
                                    cnumber = cnumber/2;
                                currentlen++;
            }
            if (currentlen > maxcyclelength)
                           maxcyclelength = currentlen;
            currentlen = 0;
    }
    cout<<atoi(argv[1])<<" "<<atoi(argv[2])<<" "<<maxcyclelength;
    return 0;
}    

[shamim]

The judge's compiler does not support the function atoi()

[chunyi81]

Add this line at the begining of your program: #include <cstdlib>