洛谷P2235 [HNOI2002]Kathy函数

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题解

// luogu-judger-enable-o2
//minamoto
#include<cstdio>
#include<cstring>
using namespace std;
const int N=;
char s[N];int n;
template<class T>inline bool cmax(T&a,const T&b){return a<b?a=b,:;}
struct node{
    int s[N];
    void clear(){
        memset(s,,sizeof(s));
    }
    void operator =(int val){
        clear();
        while(val){
            s[++s[]]=val%,val/=;
        }
    }
    void operator =(const char *str){
        int len=strlen(str);
        s[]=len;
        for(int i=;i<len;++i) s[s[]-i]=str[i]-'';
    }
    void maintain(){
        for(int i=;i<=s[];++i) if(s[i]>) s[i+]+=s[i]/,s[i]%=;
        while(s[s[]+]){
            ++s[],s[s[]+]=s[s[]]/,s[s[]]%=;
        }
    }
    void operator +=(const int &a){
        s[]+=a,maintain();
    }
    void operator +=(node a){
        cmax(s[],a.s[]);
        for(int i=;i<=s[];++i) s[i]+=a.s[i];
        maintain();
    }
    void operator -=(const int &a){
        int i=;s[i]-=a;
        while(s[i]<){
            while(s[i]<) s[i]+=,--s[i+];
            ++i;
        }
        if(!s[s[]]) --s[];
    }
    int mod(){
        return s[]&;
    }
    void div(){
        for(int i=s[];i;--i){
            if(i>&&s[i]&) s[i-]+=;
            s[i]>>=;
        }
        if(!s[s[]]) --s[];
    }
    void mul(){
        for(int i=;i<=s[];++i) s[i]*=;
        maintain();
    }
    void print(){
        for(int i=s[];i;--i) printf("%d",s[i]);
    }
}ans,res,num;
int b[N*N];
int main(){
    //freopen("testdata.in","r",stdin);
    scanf("%s",s);
    num=s;
    n=;
    while(num.s[]){
        b[n++]=num.mod(),num.div();
    }
    if(n>){
        int mid=(n-)>>;
        ans=-(n&);
        for(int i=;i<mid;++i) ans.mul();
        ans-=;
        res.clear();
        for(int i=n-;i>=n-mid-;--i) res.mul(),res+=b[i];
        bool flag=true;
        for(int i=mid;~i;--i) if(b[i]!=b[n-i-]){flag=(b[i]>b[n-i-]);break;}
        if(flag) res+=;
        ans+=res;
    }else ans=n;
    ans.print();
    return ;
}