Project euler problem 45
- by Peter
Hi, I'm not yet a skilled programmer but I thought this was an interesting problem and I thought I'd give it a go.
Triangle, pentagonal, and hexagonal
numbers are generated by the following
formulae:
Triangle T_(n)=n(n+1)/2
1, 3, 6, 10, 15, ...
Pentagonal P_(n)=n(3n-1)/2 1, 5, 12, 22, 35,
...
Hexagonal H_(n)=n(2n-1) 1,
6, 15, 28, 45, ...
It can be verified that T_(285) =
P_(165) = H_(143) = 40755.
Find the next triangle number that is
also pentagonal and hexagonal.
Is the task description.
I know that Hexagonal numbers are a subset of triangle numbers which means that you only have to find a number where Hn=Pn.
But I can't seem to get my code to work. I only know java language which is why I'm having trouble finding a solution on the net womewhere. Anyway hope someone can help. Here's my code
public class NextNumber {
public NextNumber() {
next();
}
public void next() {
int n = 144;
int i = 165;
int p = i * (3 * i - 1) / 2;
int h = n * (2 * n - 1);
while(p!=h) {
n++;
h = n * (2 * n - 1);
if (h == p) {
System.out.println("the next triangular number is" + h);
} else {
while (h > p) {
i++;
p = i * (3 * i - 1) / 2;
}
if (h == p) {
System.out.println("the next triangular number is" + h); break;
}
else if (p > h) {
System.out.println("bummer");
}
}
}
}
}
I realize it's probably a very slow and ineffecient code but that doesn't concern me much at this point I only care about finding the next number even if it would take my computer years :)
.
Peter
