# [Projecte1_] projecteuler_046

Source: Internet
Author: User
`# Pragma once # include <windows. h> class moonmath {public: moonmath (void );~ Moonmath (void ); //************************************// method: isint // access: Public // describe: determines whether the double value is very close to an integer in the Epsilon range. // if the value of 1.00005 is greater than 0.00005, It is very close to an integer. // parameter: double doublevalue: the double value to be determined. // parameter: Double Epsilon: The accuracy of the determination. If 0 <Epsilon <0.5 // parameter: int32 & intvalue is close, returns the nearest integer // returns: bool returns true, otherwise, false is returned //*********************************** * Static bool isint (double doublevalue, double Epsilon, int32 & intvalue ); //************************************// method: sign // access: Public // describe: Get the value symbol // parameter: T value to get the value of the symbol // returns: positive, 0, and negative numbers of int32 return 1, 0, and-1, respectively //************************ * *********** template <typename T> static int32 sign (T value ); //************************************// method: isprimer // access: Public // describe: determines whether a number is a prime number. // parameter: uint32 num indicates the number to be judged. // returns: bool indicates a prime number and returns true, otherwise, false is returned //*********************************** * Static bool isprimer (uint32 num ); //************************************// method: isintegersquare // access: public static // describe: determines whether the given number is an integer after the square is opened. // parameter: uint32 num // returns: bool // ************************************ static bool isintegersquare (uint32 num );};`

`# Include "moonmath. H" # include <cmath> moonmath: moonmath (void) {} moonmath ::~ Moonmath (void) {}template <typename T> int32 moonmath: Sign (T value) {If (value> 0) {return 1;} else if (value = 0) {return 0;} else {return-1 ;}} bool moonmath: isint (double doublevalue, double Epsilon, int32 & intvalue) {If (epsilon> 0.5 | Epsilon <0) {return false;} If (int32 (doublevalue + epsilon) = int32 (doublevalue-Epsilon) {return false ;} int32 value = int32 (doublevalue); intvalue = (FABS (doublevalue-value)> 0.5 )? (Value + moonmath: Sign (doublevalue): (value); Return true;} bool moonmath: isprimer (uint32 num) {// 0 and 1 are not prime if (Num <= 1) {return false;} uint32 sqrtofnum = (uint32) SQRT (double) num ); // The 2nd power of num // from 2 to SQRT (Num). If no number can be divisible by num, num is the prime number; otherwise, it is not for (uint32 I = 2; I <= sqrtofnum; ++ I) {If (Num % I = 0) {return false ;}return true ;} bool moonmath: isintegersquare (uint32 num) {uint32 qurtnum = (uint32) SQRT (double) num); Return (qurtnum * qurtnum) = num ;}`

`// Goldbach's other conjecture // problem 46 // It was proposed by Christian Goldbach that every odd composite number can be written as the sum of a prime and twice a square. /// 9 = 7 + 212 // 15 = 7 + 222 // 21 = 3 + 232 // 25 = 7 + 232 // 27 = 19 + 222 // 33 = 31 + 212 // it turns out that the conjecture was false. /// what is the smallest odd composite that cannot be written as the sum of a prime and Twice a square? # Include <iostream> # include <windows. h> # include <ctime> # include <assert. h> # include <moonmath. h> using namespace STD; // class detailprinter {public: void start (); void end (); detailprinter (); Private: large_integer timestart; large_integer timeend; large_integer freq ;}; detailprinter: detailprinter () {queryperformancefrequency (& freq );} //************************************// method: start // ACC ESS: Public // describe: called before each method is executed // returns: void // *********************************** void detailprinter:: Start () {queryperformancecounter (& timestart );} //************************************// method: end // access: Public // describe: Call each method after execution // returns: void // *********************************** void detailprinter:: end () {queryperformancecounter (& timeend); cout <"Total milliseconds is" <(Dou BLE) (timeend. quadpart-timestart. quadpart) * 1000/freq. quadpart <Endl; time_t currenttime = Time (null); const char beep_char = '\ 007'; const int max_time_char = 30; char timestr [max_time_char]; ctime_s (timestr, max_time_char, extends tTime); cout <Endl <"by godmoon" <Endl <timestr <beep_char; System ("pause ");} ************ *********************///*************** * ****************** // Method: isfitconjecture/Access: Public // describe: determine whether num meets the conjecture // parameter: uint32 num // returns: bool // *********************************** bool isfitconjecture (uint32 num) {// if it is a prime number, it matches the conjecture that if (moonmath: isprimer (Num) {return true ;}for (uint32 I = 0; I <num; I ++) {// exclude non-prime if (! Moonmath: isprimer (I) {continue;} // determine whether (Num-I)/2 is an integer square if (moonmath: isintegersquare (Num-I) /2) {return true;} return false;} void testfun1 () {cout <"test OK! "<Endl;} void F1 () {cout <" Void F1 () "<Endl; // testfun1 (); detailprinter. start (); /********************************** algorithm start **** * **************************/const uint32 start_odd_num = 3; uint32 I = start_odd_num; while (isfitconjecture (I) {I + = 2 ;} cout <"the smallest odd composite that cannot be written as the sum of a prime and twice a square is:" <Endl <I <Endl; /*********************************** end of the algorithm **** * **************************/detailprinter. end () ;}// main function int main () {F1 (); Return 0 ;}/ * void F1 () the smallest odd composite that cannot be written as the sum of a prime and twice a square is: 5777 total milliseconds is 62.9729by godmoonsun Mar 10 22:26:17 2013 */`

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