Educational Codeforces Round 116 (Rated for Div. 2)

我进行了分类讨论大于100000000000000一类，小于100000000000000一类；

#include<bits/stdc++.h>
#define ll long long
using namespace std;
int main(){
    int t;
    scanf("%d",&t);
    while(t--){
        ll k=0,a,b,sum,n,ans=0;
        scanf("%lld %lld",&a,&b);
        sum=1,n=0;
        if(a<100000000000000){
            for(int i=0;;i++){            
                if(k<b){
                     k=pow(2,i);
                     if(k>b){
                         k=b;
                    }
                }
                else k=b;
                sum+=k;    
                if(a==1&&b>0){
                     printf("0\n");
                     break;
                }
                if(a>sum){
                     n++;
                }
                else if(a==sum){
                     printf("%lld\n",n+1);
                     break;
                } 
                else if(a<sum){
                     printf("%lld\n",n+1);
                     break;
                }
            }
        }
        else {
            if(a==1) printf("0\n");
            else if(b==1) printf("%lld\n",a-1);
            for(int i=0;a>1&&b>1;i++){             
                if(k<b){
                    k=pow(2,i);
                if(k>b){
                    k=b;
                }
                sum+=k;
                if(a>sum){
                    n++;        
                }
                if(a<=sum){
                    printf("%lld\n",n+1);
                    break;
                    }     
                }
                else break;
            }
            if(a>sum&&a!=1&&b!=1){
                sum=a-sum;
                ans=sum%b;
                sum/=b;
                if(ans==0){
                    printf("%lld\n",sum+n);
                }
                else printf("%lld\n",sum+n+1);
            }
        }
    }
    return 0;
}