BZOJ 4029 [HEOI2015]定价

题解：

！！！！！！

分类讨论，情况挺多

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
typedef long long Lint;

int TT; 
Lint L,R;

int A[100];
int B[100];
int C[100];

int main(){
    scanf("%d",&TT);
    while(TT--){
        memset(A,0,sizeof(A));
        memset(B,0,sizeof(B));
        memset(C,0,sizeof(C));
        scanf("%lld%lld",&L,&R);
        Lint x;
        int lenA=0;
        x=L;
        while(x){
            A[++lenA]=x%10;
            x/=10;
        }
        int lenB=0;
        x=R;
        while(x){
            B[++lenB]=x%10;
            x/=10;
        }
        
        if(lenA==lenB){
            for(int i=lenA;i>=1;--i){
                if(A[i]==B[i]){
                    C[i]=A[i];
                }else{
                    int all0=1;
                    for(int j=1;j<=i-1;++j)if(A[j]!=0)all0=0;
                    if(A[i]==0){
                        if(all0){
                            C[i]=0;
                        }else{
                            if(B[i]>=5){
                                C[i]=5;
                            }else{
                                C[i]=1;
                            }
                        }
                    }else{
                        if(((A[i]<5)||((A[i]==5)&&(all0)))&&(B[i]>=5)){
                            C[i]=5;
                        }else{
                            if(all0){
                                C[i]=A[i];
                            }else{
                                C[i]=A[i]+1;
                            }
                        }
                    }
                    break;
                }
            }
            for(int i=lenA;i>=1;--i)printf("%d",C[i]);
            cout<<endl;
        }else{
            Lint x=5;
            while(x<L)x*=10;
            if(x<=R){
                printf("%lld\n",x);
            }else{
                int all0=1;
                for(int i=1;i<lenA;++i)if(A[i]!=0)all0=0;
                if(all0)x=A[lenA];
                else x=A[lenA]+1;
                while(x<L)x*=10;
                printf("%lld\n",x);
            }
        }
        
    }
    return 0;
}