Project Euler - Problem 31

#include <iostream>#include <time.h>#include <math.h>#include <set>#include <list>using namespace std;int main(){double start = clock(),end(0);int count = 0;for(int a = 0; a<=1; a++)//200{for(int b = 0; b<=2; b++)//100{for(int c = 0; c<=4 ;c++)//50{for(int d = 0; d<=10 ;d++)//20{for(int e = 0; e<=20 ;e++)//10{for(int f = 0; f<=40 ;f++)//5{for(int g = 0; g<=100 ;g++)//2{for(int h = 0; h<=200 ;h++)//1{if(h*1+g*2+f*5+e*10+d*20+c*50+b*100+a*200 == 200){count++;cout<<a<<","<<b<<","<<c<<","<<d<<","<<e<<","<<f<<","<<g<<","<<h<<endl;}}}}}}}}}cout << endl << "answer is "<< count <<endl;end = clock();double result = (end - start)/1000;cout.setf(ios::fixed);cout <<endl<< "3.00GHz's run time = " << result << "s."<<endl;return 0;} 144s

 

#include <iostream>#include <time.h>#include <math.h>#include <set>#include <list>using namespace std;int main(){double start = clock(),end(0);int times[201] = {0};for(int n =-1; n <= 200;){if(n<21)++n;if(n==21)n+=9;int cnt = 0;for(int a = 0; a<=200; a++){for(int b = 0; b<=200; b++){for(int c = 0; c<=200; c++){if(n == a + 2*b + 5*c){cnt++;}}}}times[n] = cnt;//cout << "n = "<< n << " , cnt = " << cnt<<endl;if(n>21)n+=10;}int sum = 0;for(int x =0,y=20; x!=210, y!=-1; x+=10,y--){//cout << "times["<<x<<"] = "<<times[x]<< " * times["<<y<<"] = "<<times[y]<<endl;sum += times[x] * times[y];}for(int x =0,y=10; x!=110, y!=-1; x+=10,y--){//cout << "times["<<x<<"] = "<<times[x]<< " * times["<<y<<"] = "<<times[y]<<endl;sum += times[x] * times[y];}cout << "sum = " << sum+2 << endl;end = clock();double result = (end - start)/1000;cout.setf(ios::fixed);cout <<endl<< "3.00GHz's run time = " << result << "s."<<endl;return 0;} 1s

int count=0; int a, b, c, d, e, f, g; int m =200;for( a=m ; a>=0 ; a -= 200 ) for( b=a ; b>=0 ; b -= 100 ) for( c=b ; c>=0 ; c -= 50 ) for( d=c ; d>=0 ; d -= 20 ) for( e=d ; e>=0 ; e -= 10 ) for( f=e ; f>=0 ; f -= 5 ) for( g=f ; g>=0 ; g -= 2 ) count++; cout << count; 0s