PE45

/*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)/21, 5, 12, 22, 35, ...Hexagonal H(n) = n(2n-1) 1, 6, 15, 28, 45, ...It can be verified that T285 = P165 = H143 = 40755.Find the next triangle number that is also pentagonal and hexagonal.*/#include <iostream>#include <windows.h>using namespace std;typedef unsigned long long int _INT64 ;const _INT64 nSIZE = 100000;int main(){__int32 startTime = GetTickCount();_INT64 lastP = 166;for (_INT64 h = 144; h<nSIZE; h++){_INT64 HN = h*(2*h-1);for (_INT64 p = lastP; ; p++){_INT64 PN = p*(3*p-1)/2;if (HN==PN){cout << HN << '/n';__int32 endTime = GetTickCount();cout << "the running time = " << endTime-startTime << " ms.";return 0;}if (PN > HN){lastP = p;break;}}}return 0;}