欧拉项目#27
Project Euler #27
本文关键字:项目 更新时间:2023-10-16
我在欧拉项目中挑战自己,但目前卡在问题27上,其中问题说明:
欧拉发表了非凡的二次公式:
n²+ n + 41
结果表明,对于n = 0到39的连续值,该公式将产生40个素数。然而,当n = 40时,402 + 40 + 41 = 40(40 + 1)+ 41能被41整除,当n = 41时,41²+ 41 + 41显然能被41整除。
使用计算机,发现了令人难以置信的公式n²79n + 1601,它为n = 0到79的连续值产生80个素数。系数79和1601的乘积为126479。
考虑如下形式的二次方程:
n²+ an + b,其中|a| 1000和|b| 1000
其中|n|为n的模/绝对值例如|11| = 11和|4| = 4求系数a和系数b的乘积,求二次表达式产生>从n = 0开始的连续n值的最大素数
我写了下面的代码,它给了我很快的答案,但它是错误的(它吐出我(-951)*(-705)= 670455)。有人可以检查我的代码,看看我的错误在哪里?
#include <iostream>
#include <vector>
#include <cmath>
#include <time.h>
using namespace std;
bool isprime(unsigned int n, int d[339]);
int main()
{
clock_t t = clock();
int c[] = {13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,89,97,101,103,107,109,113,127,131,137,139,149,151,157,163,167,173,179,181,191,193,197,199,211,223,227,229,233,239,241,251,257,263,269,271,277,281,283,293,307,311,313,317,331,337,347,349,353,359,367,373,379,383,389,397,401,409,419,421,431,433,439,443,449,457,461,463,467,479,487,491,499,503,509,521,523,541,547,557,563,569,571,577,587,593,599,601,607,613,617,619,631,641,643,647,653,659,661,673,677,683,691,701,709,719,727,733,739,743,751,757,761,769,773,787,797,809,811,821,823,827,829,839,853,857,859,863,877,881,883,887,907,911,919,929,937,941,947,953,967,971,977,983,991,997,1009,1013,1019,1021,1031,1033,1039,1049,1051,1061,1063,1069,1087,1091,1093,1097,1103,1109,1117,1123,1129,1151,1153,1163,1171,1181,1187,1193,1201,1213,1217,1223,1229,1231,1237,1249,1259,1277,1279,1283,1289,1291,1297,1301,1303,1307,1319,1321,1327,1361,1367,1373,1381,1399,1409,1423,1427,1429,1433,1439,1447,1451,1453,1459,1471,1481,1483,1487,1489,1493,1499,1511,1523,1531,1543,1549,1553,1559,1567,1571,1579,1583,1597,1601,1607,1609,1613,1619,1621,1627,1637,1657,1663,1667,1669,1693,1697,1699,1709,1721,1723,1733,1741,1747,1753,1759,1777,1783,1787,1789,1801,1811,1823,1831,1847,1861,1867,1871,1873,1877,1879,1889,1901,1907,1913,1931,1933,1949,1951,1973,1979,1987,1993,1997,1999,2003,2011,2017,2027,2029,2039,2053,2063,2069,2081,2083,2087,2089,2099,2111,2113,2129,2131,2137,2141,2143,2153,2161,2179,2203,2207,2213,2221,2237,2239,2243,2251,2267,2269,2273,2281,2287,2293,2297,2309,2311};
int result[4];
result[3] = 0;
for (int a = -999; a < 1000; a+=2)
{
for (int b = -999; b < 1000; b+=2)
{
bool prime;
int n = 0, count = 0;
do
{
prime = isprime(n*n + a*n + b, c);
n++;
count++;
} while (prime);
count--;
n--;
if (count > result[3])
{
result[0] = a;
result[1] = b;
result[2] = n;
result[3] = count;
}
}
if ((a+1) % 100 == 0)
cout << a+1 << endl;
}
cout << result[0] << endl << result[1] << endl << result[2] << endl << result[3] << endl << clock()-t;
cin >> result[0];
return 0;
}
bool isprime(unsigned int n, int d[339])
{
int j = 0, l;
if ((n == 2) || (n == 3) || (n == 5) || (n == 7) || (n == 11))
return 1;
if ((n % 2 == 0) || (n % 3 == 0) || (n % 5 == 0) || (n % 7 == 0) || (n % 11 == 0))
return 0;
while (j <= int (sqrt(n) / 2310))
{
for (int k = 0; k < 339; k++)
{
l = 2310 * j + d[k];
if (n % l == 0)
return 0;
}
j++;
}
return 1;
}
isprime函数有一个bug。
在你的函数中,你检查所有2310 * j + d[k],其中j
例如,当a = 1, b = 41, n = 0时,你的函数将从j = 0开始检查41是否为素数。因此也验证了41是否能被2310 * 0 + d[7] = 41整除,从而得出假返回。
This version should be correct:
bool isprime(unsigned int n, int d[])
{
int j = 0, l;
if ((n == 2) || (n == 3) || (n == 5) || (n == 7) || (n == 11))
return 1;
if ((n % 2 == 0) || (n % 3 == 0) || (n % 5 == 0) || (n % 7 == 0) || (n % 11 == 0))
return 0;
double root = sqrt(n);
while (j <= int (root / 2310))
{
for (int k = 0; k < 339; k++)
{
l = 2310 * j + d[k];
if (l < root && n % l == 0)
return 0;
}
j++;
}
return 1;
}
相关文章:
- 使用C++库在Android项目中修改gradle中的cmake参数,用于插入指令的测试
- 无法在 CLion 中构建 C++ 项目
- 运行同一解决方案的另一个项目的项目
- CMake-按正确顺序将项目与C运行时对象文件链接
- 如何在选项卡视图Qt中设置一个新项目,并保存以前的项目
- 欧拉项目#8答案是大以获得有效答案
- 从链接列表c++中删除一个项目
- CMake项目Boost库错误:Boost/config/compiler/gcc.hpp:165:10:致命错误:cs
- 既然存在危险,为什么项目要使用-I include开关
- cmake在我的项目中所需的所有静态库都不成功
- QT通过C++添加映射QML项目
- 我的项目不会像"undefined reference to `grpc::g_core_codegen_interface'"那样使用未定义的引用错误进行编译
- 在linux上调试巨大的C++项目
- 在其他文件中创建类时在 c++ 项目中不起作用
- 使外部项目可用于find_package CMake
- 在子目录中使用target_sources()命令时用于单元测试(qtest)的项目结构
- 使用外部SDK工具链文件在VisualStudio上生成项目编译错误
- 如何维护资源管理器项目视图中当前可见的项目列表
- 错误-我无法在VS2019中打开新的Qt项目
- 你能检查一下为什么在这个代码中从链接列表中删除项目不起作用吗