4个超时，求大佬指导优化~！

#include<iostream>

#include<cstdio>

#include<cmath>

using namespace std;

void chengfa();

void print();

int p,i,a[505];

int main(){

    a[1]=1;
    cin>>p;
    for(int i=1;i<=p;++i)
        chengfa();
    a[1]-=1;
    print();
    return 0;
}
void print(){

    cout<<(int)(p*log(2)/log(10))+1<<endl;
    i=500;
    while(i){
        cout<<a[i--];
        if(i%50==0)
            cout<<endl; 
    }
}
void chengfa(){

    int x=0;
    for(i=1;i<=500;++i){
        a[i]=a[i]*2+x;
        x=a[i]/10;
        a[i]%=10;
    }
 }