math数学部分

int gcd(int a,int b)//普通方法
{
int m,n,r;
m=a>=b?a:b;//m>=n
n=a<b?a:b;
r=m%n;
while(r!=0)
{
m=n;
n=r;
r=m%n;
}
return n;
}

int lcm(int a,int b)
{
return a/gcd(a,b)*b;
}

int gcdcore(int a,int b)
{
if (a==0) return b;
if (b==0) return a;
while ((a & 0x1)==0)
{
a=a>>1;
}
if (a<b)
{
b=(b-a)>>1;
return gcdcore(b,a);
}
else
{
a=(a-b)>>1;
return gcdcore(a,b);
}
}
int gcd_fast(int a,int b)//stein算法+位运算优化
{
int c=0;
while (((a & 0x1)==0)&&(( b & 0x1 )==0))
{
a=a>>1;
b=b>>1;
c++;
}
if ((a & 0x1) == 0)
{
a=a>>1;
return gcdcore(a,b)<<c;
}
else
return gcdcore(b,a)<<c;

}

int ex_gcd(int a,int b,int &x,int &y)
{
int tmp,ans;
if(b==0)
{
x=1;
y=0;
return a;
}
ans=ex_gcd(b,a%b,x,y);
tmp=x;
x=y;
y=tmp-(a/b)*y;
return ans;
}

int exgcd(int m,int n,int &x,int &y)//迭代形式
{
int x1,y1,x0,y0;
x0=1; y0=0;
x1=0; y1=1;
x=0; y=1;
int r=m%n;
int q=(m-r)/n;
while(r)
{
x=x0-q*x1; y=y0-q*y1;
x0=x1; y0=y1;
x1=x; y1=y;
m=n; n=r; r=m%n;
q=(m-r)/n;
}
return n;
}

int cal(int a,int m)//乘法逆元
{
int x,y;
int gcd=ex_gcd(a,m,x,y);
if(1%gcd!=0)
return -1;
x*=1/gcd;
m=abs(m);
int ans=x%m;
if(ans<=0)
ans+=m;
return ans;
}