bzoj1876 SuperGCD

#include<cstdio>
#include<cstring>
#define B 1000000000
const int B9=B-1;
char s[10010];
struct num{
    int a[1200];
    int l;
    num(){l=0;}
    inline void div2(){
        for(int i=l;i>0;i--){
            if(a[i]&1)a[i-1]+=B;
            a[i]>>=1;
        }
        a[0]>>=1;
        while(l&&!a[l])--l;
    }
    inline void mut2(){
        for(int i=0;i<=l;i++)a[i]<<=1;
        for(int i=0;i<=l;i++)a[i+1]+=a[i]/B,a[i]%=B;
        if(a[l+1])l++;
    }
    void print(){
        printf("%d",a[l]);
        for(int i=l-1;i>=0;i--)printf("%09d",a[i]);
    }
}a1,b1;
inline bool operator<(num&a,num&b){
    for(int i=a.l<b.l?b.l:a.l;i>=0;i--){
        if(a.a[i]<b.a[i])return true;
        if(a.a[i]>b.a[i])return false;
    }
    return false;
}
inline bool operator-=(num&a,num&b){
    a.a[0]+=1;
    for(int i=a.l;i>=0;i--)a.a[i]+=B9-b.a[i];
    for(int i=0;i<a.l;i++)a.a[i+1]+=a.a[i]/B,a.a[i]%=B;
    a.a[a.l]%=B;
    while(a.l&&!a.a[a.l])--a.l;
}
num*a=&a1,*b=&b1,*c;
int t2=0,l;
int p10[]={1,10,100,1000,10000,100000,1000000,10000000,100000000};
int main(){
    scanf("%s",s);
    l=strlen(s)-1;
    for(int i=0;i<=l;i++)a->a[(l-i)/9]+=p10[(l-i)%9]*(s[i]-‘0‘);
    a->l=l/9;
    if(a->a[a->l+1])a->l++;
    scanf("%s",s);
    l=strlen(s)-1;
    for(int i=0;i<=l;i++)b->a[(l-i)/9]+=p10[(l-i)%9]*(s[i]-‘0‘);
    b->l=l/9;
    if(b->a[b->l+1])b->l++;
    while(!(a->a[0]&1)&&!(b->a[0]&1)){
        t2++;
        a->div2();
        b->div2();
    }
    do{
        while(!(a->a[0]&1))a->div2();
        while(!(b->a[0]&1))b->div2();
        if(*a<*b)c=a,a=b,b=c;
        *a-=*b;
    }while(a->l!=0||a->a[0]!=0);
    while(t2--)b->mut2();
    b->print();
    return 0;
}