差值最小 - 编程论坛

#2

rjsp2023-09-29 22:50

在n前后找素数

#3

风卷浪起2023-09-30 15:30

谢谢！

#4

风卷浪起2023-09-30 15:51

能不能给个具体的代码

#5

风卷浪起2023-10-01 22:12

我做出来了！
（有点复杂）
#include <bits/stdc++.h>
using namespace std;
long long a[5], b[5];
bool prime(int n)
{
    for (int i = 2; i <= sqrt(n); i ++)
    {
        if (n % i == 0)
        {
            return false;
        }
    }
    return true;
}
int find_prime(int n, int f)
{
    int i = n+f;
    while (!prime(i))
    {
        i += f;
    }
    return i;
}
int main()
{
    int n, num1, num2;
    cin >> n;
    if (prime(n))
    {
        a[1] = find_prime(n, -1);
        a[0] = find_prime(a[1], -1);
        a[2] = n;
        a[3] = find_prime(a[2], 1);
        a[4] = find_prime(a[3], 1);
        cout << a[0] << endl;
        cout << a[1] << endl;
        cout << a[2] << endl;
        cout << a[3] << endl;
        cout << a[4] << endl;
    }
    else
    {
        a[1] = find_prime(n, -1);
        a[0] = find_prime(a[1], -1);
        a[2] = find_prime(a[1], 1);
        a[3] = find_prime(a[2], 1);
        a[4] = find_prime(a[3], 1);
        num1 = abs(a[0] + a[1] + a[2] + a[3] + a[4] - 5 * n);
        b[2] = find_prime(n, -1);
        b[1] = find_prime(b[2], -1);
        b[0] = find_prime(b[1], -1);
        b[3] = find_prime(b[2], 1);
        b[4] = find_prime(b[3], 1);
        num2 = abs(b[0] + b[1] + b[2] + b[3] + b[4] - 5 * n);
        if (num1 > num2)
        {
            cout << b[0] << endl;
            cout << b[1] << endl;
            cout << b[2] << endl;
            cout << b[3] << endl;
            cout << b[4] << endl;
        }
        else
        {
            cout << a[0] << endl;
            cout << a[1] << endl;
            cout << a[2] << endl;
            cout << a[3] << endl;
            cout << a[4] << endl;
        }
    }
}

#6

apull2023-10-01 23:32

稍微改了下你的代码，供参考

程序代码：

bool prime(int n)
{
    for (int i = 2; i <= sqrt(n); i++)
    {
        if (n % i == 0)
        {
            return false;
        }
    }
    return true;
}

void  find_prime(int *a, int n)
{
    int i = n, cnt = 4, f = -1;
    while (cnt < 10)
    {
        if (prime(i))
        {
            a[cnt] = i;
            cnt += f;
            if (cnt == 0)
            {
                i = n;
                f = 1;
                cnt = 5;
            }
        }
        i += f;
    }
}

int main()
{
    int a[10];
    int n, num1, num2, min, t, inx = 0;
    cin >> n;
    find_prime(a, n);
    min = num1 = 5 * n;

    for (int i = 0; i <= 6; i++)
    {
        num2 = 0;
        for (int j = 0; j < 5; j++)
            num2 += a[i + j];

        t = abs(num1 - num2);
        if (t < min)
        {
            min = t;
            inx = i;
        }
    }

    for (int i = inx; i < inx + 5; i++)
        cout << a[i] << endl;
}

[此贴子已经被作者于2023-10-1 23:34编辑过]

#7

风卷浪起2024-02-24 21:40

谢谢