problem 12 f(n) = f(n-1) + n 数列中第一个

projecteuler.net/problems

#include <iostream>#include <cstdio>#include <cmath>using namespace std;long long SumFactor(long long n){long long ans = 0;long long i;long long end = sqrt(n + 0.0) + 1;//可大大减少时间开销for(i = 1; i <=end ; i++){if(n % i == 0){ans+=2;}if(ans>=500){return 1;}}//cout<<ans<<endl;if(ans >= 499){return 1;}else{return 0;}}int   main(){long long i = 1;long long natural = 2;while(i){if(SumFactor(i)){break;}i += natural;natural++;}printf("%lld\n",i);return 0;}