7.4 gcd

# include<stdio.h>
int main()
{
int gcd(int a,int b);
int n,i,x,y,c;
scanf("%d",&n);
for(i=1;i<=n;i++)
{
if(i==1)
{
scanf("%d",&x);
}
else
{
scanf("%d",&y);
c =x ;
c = gcd(y,c); 
x = c;
}
}
printf("%d",c);
}

int gcd(int a,int b)
{
int d,r;
if(a<b){d=a;a=b;b=d;}
if(b==0){return a; ////少了这一句会出现除数为0 的情况   0与其他数的最大公约数 为这个数本身
}
r=a%b;
while(r)
{
a=b;b=r;r=a%b;
}
return b;
}