OneMoreError - 3 years ago 124

Java Question

I am trying to find the Largest prime factor of a number while solving this problem here. I think that I am doing everything right, however one of the test case (#2) is failing and I can't think of any corner case where it might fail. Here's my code, please have a look and try to spot something.

`public class ProblemThree`

{

public static void main(String[] args)

{

Scanner scanner = new Scanner(System.in);

int T = scanner.nextInt();

for (int i = 0; i < T; i++)

{

System.out.println(largestPrime(scanner.nextLong()));

}

}

private static long largestPrime(long n)

{

while (n % 2 == 0)

{

n = n / 2; // remove all the multiples of 2

}

while (n % 3 == 0)

{

n = n / 3; // remove all the multiples of 2

}

// remove multiples of prime numbers other than 2 and 3

while (n >= 5)

{

boolean isDivisionComplete = true;

for (long i = 5; i < Math.ceil(Math.sqrt(n)); i++)

{

if (n % i == 0)

{

n = n / i;

isDivisionComplete = false;

break;

}

}

if (isDivisionComplete)

{

break;

}

}

return n;

}

}

Basically, what I am doing is:

`Largest_Prime(n):`

1. Repeatedly divide the no by any small number, say x where 0 < x < sqrt(n).

2. Then set n = n/x and repeat steps 1 and 2 until there is no such x that divides n.

3 Return n.

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Answer Source

It seems you have some bug in your code as as when you input **16** *largestPrime* function return 1. and this is true for when input is the power of 3.

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