ionchy
/
projecteuler
1
0
Fork 0
Code

Problem 45

This commit is contained in:
Jonathan Chan 2016-12-07 09:50:25 -08:00
parent 36c2236e3f
commit 8ffef23d48
2 changed files with 22 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

BIN
45 Executable file
View File

Binary file not shown.

22
45.c Normal file
View File

@ -0,0 +1,22 @@
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <stdbool.h>
bool isPentagonal (long long n) {
long long radicand = 24*n + 1;
long long sqrtr = sqrt (radicand);
return sqrtr * sqrtr == radicand && (sqrtr + 1) % 6 == 0;
}
int main () {
long long n = 144LL;
while (true) {
long long hex = n * (2*n - 1);
if (isPentagonal (hex)) {
printf ("%lli\n", hex);
break;
}
n++;
}
}