CDU集训代码：初等数论

做题地址：http://acm.hdu.edu.cn/diy/contest_login.php?cid=16649

 

Problem K： HDU 1061

//计算+规律，可以用纯规律

for(i=0; i<N%4-1; i++)  N%4是规律推出来的最小公倍数

#include <stdio.h>

int main()
{
    int T, N, i, ans, tmp;
    scanf("%d", &T");
    while(T--)
    {
        scanf("%d", &N");
        if(N>10)
            tmp = N%10;
        else
            tmp = N;
        ans = tmp;
        for(i=0; i<N%4-1; i++)
        {
            ans *=tmp;
            if(ans>10)
                ans %= 10;
        }
        printf("%d\n", ans);
    }
    return 0;
}

 

纯规律做这道题

#include <stdio.h>

int main ()
{
    int t;
    scanf ("%d", &t");
    while ( t -- )
    {
        int n, a;
        scanf ("%d", &n");
        a = n % 10;
        if ( a == 0 )
            puts("0");
        else if ( a == 1 )
            puts("1");
        else if ( a == 5 )
            puts("5");
        else if ( a == 6 )
            puts("6");
        else if ( a == 2 )
        {
            if ( n % 4 == 0 )
                puts("6");
            else if ( n % 4 == 1 )
                puts("2");
            else if ( n % 4 == 2 )
                puts("4");
            else if ( n % 4 == 3 )
                puts("8");
        }
        else if ( a == 3 )
        {
            if ( n % 4 == 0 )
                puts("1"); 
            else if ( n % 4 == 1 )
                puts("3");
            else if ( n % 4 == 2 )
                puts("9");
            else if ( n % 4 == 3 )
                puts("7");
        }

        else if ( a == 4 )
        {
            if ( n % 2 == 0 )
                puts("6");
            else if ( n % 2 == 1 )
                puts("4");
        }

        else if ( a == 7 )
        {
            if ( n % 4 == 0 )
                puts("1");
            else if ( n % 4 == 1 )
                puts("7");
            else if ( n % 4 == 2 )
                puts("9");
            else if ( n % 4 == 3 )
                puts("3");
        }

        else if ( a == 8 )
        {
            if ( n % 4 == 0 )
                puts("6");
            else if ( n % 4 == 1 )
                puts("8");
            else if ( n % 4 == 2 )
                puts("4");
            else if ( n % 4 == 3 )
                puts("2");
        }

        else if ( a == 9 )
        {
            if ( n % 2 == 0 )
                puts("1");
            else if ( n % 2 == 1 )
                puts("9");
        }
    }
   return 0;
}

 

 

Problem H：HDU 2114

求1到N的立方和

#include <stdio.h>

int main()
{
    __int64 sum,n;
    while(scanf("%I64d",&n)!=EOF)
    {
        sum = 0;
        if(n>10000)
            n = n%10000;
        sum = (n*(n+1)/2)*(n*(n+1)/2);
        sum = sum%10000;
        printf("%04I64d\n",sum);
    }
    return 0;
}

 

 

Problem C： HDU 1222

#include <stdio.h>

int main()
{
    int t,m,n;
    scanf("%d",&t);
    while(t--)
    {
        scanf("%d%d",&m,&n);
        while(m>n?(m%=n):(n%=m));
        if(m+n==1) 
            printf("NO\n");
        else 
            printf("YES\n");
    }
    return 0;
}