https://vjudge.net/problem/POJ-3208

The number 666 is considered to be the occult “number of the beast” and is a well used number in all major apocalypse themed blockbuster movies. However the number 666 can’t always be used in the script so numbers such as 1666 are used instead. Let us call the numbers containing at least three contiguous sixes beastly numbers. The first few beastly numbers are 666, 1666, 2666, 3666, 4666, 5666…

Given a 1-based index n, your program should return the nth beastly number.

就是求第n小的包含三个连续的6的数

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辣鸡poj，死活登不进

vjudge访问速度比肩外星网站

国内大学排名第一就可以为所欲为吗？？？？？？？？？？？？？？？？？？？？？？？？

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#include<iostream>
#include<cstdio>

#define ri register int
#define u long long

namespace opt {

    inline u in() {
        u x(0),f(1);
        char s(getchar());
        while(s<'0'||s>'9') {
            if(s=='-') f=-1;
            s=getchar();
        }
        while(s>='0'&&s<='9') {
            x=(x<<1)+(x<<3)+s-'0';
            s=getchar();
        }
        return x*f;
    }

}

using opt::in;

#include<cstring>

namespace mainstay {

    u f[30][4],ans[30];

    inline void solve() {
        u T(in());
        f[0][0]=1;
        for(ri i(1); i<=20; ++i) {
            f[i][0]=9*(f[i-1][0]+f[i-1][1]+f[i-1][2]);
            f[i][1]=f[i-1][0];
            f[i][2]=f[i-1][1];
            f[i][3]=10*f[i-1][3]+f[i-1][2];
        }
        while(T--) {
            u _a(in()),_m(1),flg(0);
            for(; f[_m][3]<_a; ++_m);
            for(ri i(_m); i>=1; --i) {
                u _t(0);
                for(ri j(0); j<=9; ++j) {
                    _t=f[i-1][3];
                    u _flg(0);
                    if(flg) _t+=f[i-1][0]+f[i-1][1]+f[i-1][2];
                    else if(j==6) {
                        u k(i);
                        for(; k+1<=_m&&ans[k+1]==6; ++k);
                        if(k-i>=2) _flg=1;
                        for(ri p(i); p<=k&&p-i+1<=3; ++p)
                            _t+=f[i-1][3-(p-i+1)];
                    }
                    if(_t<_a) {
                        _a-=_t;
                    } else {
                        ans[i]=j;
                        if(j==6&&_flg) flg=1;
                        std::cout<<j;
                        break;
                    }
                }
            }
            printf("\n");
        }
    }

}


int main() {

    //freopen("f.in","r",stdin);
    //freopen("f.out","w",stdout);
    mainstay::solve();

}