UVA 10738 Riemann vs Mertens

Fucker — Fri, 08 Oct 2010 08:23:00 GMT

简单题，看懂题意就好，定义了一个莫比乌斯函数，让你求该函数的值。预处理的时候在素数筛选的时候忘记给大于m[i]赋值了，错了好几次。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define N 1000005

bool p[N];
int m[N], M[N], prime[N / 10], top;
int factor[32];

void sieve()
{
    memset(p, 1, sizeof(p));
    p[0] = p[1] = top = 0;
    m[1] = 1;
    for(int i = 2; i < 1001; i++)
    {
        if(p[i])
        {
            m[i] = -1;//就这里，只给1000以内的素数赋值，错了几次
            prime[top++] = i;
            for(int j = i * i; j < N; j += i) p[j] = 0;
        }
    }
    for(int i = 4; i < N; i++)
    {
        if(p[i])
        {
            m[i] = -1;
            continue;
        }
        int t = i, k = 0, mk = 0;
        for(int j = 0; prime[j] < t && j < top; j++)
        {
            while(t % prime[j] == 0)
            {
                factor[k++] = prime[j];
                t /= prime[j];
            }
        }
        if(t != 1) factor[k++] = t;
        for(int j = 1; j < k; j++)
        {
        //    printf("%d: %d\n", i, factor[j - 1]);
        //    system("pause");
            if(factor[j] == factor[j - 1])
            {
                mk = 1;
                break;
            }
        }
        if(mk) continue;
        if(k & 1) m[i] = -1;
        else m[i] = 1;
    }
    for(int i = 1; i < N; i++) M[i] = M[i - 1] + m[i];
}

int main()
{
//    freopen("out.txt", "w", stdout);
    sieve();
    int n;
    while(scanf("%d", &n), n)
    {
        printf("%8d%8d%8d\n", n, m[n], M[n]);
    }
    return 0;
}

Fucker 2010-10-08 16:23 发表评论

SGU 102 Coprimes

Fucker — Thu, 20 May 2010 02:44:00 GMT

水题，暴力枚举即可，欧拉函数也可以，不过数据范围较小。

#include <stdio.h>

int gcd(int a, int b)
{
    return a % b == 0 ? b : gcd(b, a % b);
}

int main()
{
    int n, ans;
    while(~scanf("%d", &n))
    {
        ans = 0;
        for(int i = 1; i <= n; i++)
        {
            if(gcd(i, n) == 1) ans++;
        }
        printf("%d\n", ans);
    }
    return 0;
}

Fucker 2010-05-20 10:44 发表评论

C++博客-syhd142-文章分类-数论

UVA 10738 Riemann vs Mertens

SGU 102 Coprimes