Editorial for Dãy số


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Lưu ý: Các code mẫu dưới đây chỉ mang tính tham khảo và có thể không AC được bài tập này

Code mẫu của flashmt

#include <iostream>
#include <algorithm>
#include <sstream>
#include <string>
using namespace std;

int modify(int x)
{
    string s;
    stringstream ss;
    ss << x; ss >> s;
    sort(s.begin(),s.end());
    ss.clear();
    ss << s; ss >> x;
    return x;
}

int f[100], d[1000100], period, start;

int main()
{
    f[1] = 1; d[1] = 1;
    for (int i = 2; i < 100; i++)
    {
        f[i] = modify(f[i-1] * 2);
        if (!d[f[i]]) d[f[i]] = i;
        else period = i - d[f[i]], start = d[f[i]];
    }

    int n;
    cin >> n;
    if (n < start) cout << f[n] << endl;
    else cout << f[start + (n - start) % period] << endl;
}

Code mẫu của happyboy99x

#include<cstdio>

int f[] = {1, 2, 4, 8, 16, 23, 46, 29, 58, 116, 223, 446, 289, 578, 1156, 1223, 2446, 2489, 4789, 5789, 11578, 12356, 12247, 24449, /**/48889/**/, 77789, 155578, 111356, 122227, 244445};

int main() {
    int n; scanf("%d", &n);
    if(n <= 24) printf("%d\n", f[n-1]);
    else printf("%d\n", f[(n - 25) % 6 + 24]);
    return 0;
}

Code mẫu của ladpro98

program c11seq3;
uses    sysutils;
var     f:array[1..30] of longint;
        i,n:longint;
        s:string;

function sort(s:string):string;
var     k:string;
        t:char;
        i,j:longint;
begin
        for i:=1 to length(s)-1 do
        for j:=i+1 to length(s) do
        if s[i]>s[j] then
        begin
                t:=s[i];
                s[i]:=s[j];
                s[j]:=t;
        end;
        exit(s);
end;

begin
        f[1]:=1;
        readln(n);
        for i:=2 to 30 do
        begin
                f[i]:=f[i-1]*2;
                s:=sort(inttostr(f[i]));
                f[i]:=strtoint(s);
        end;
        if n<=24 then writeln(f[n])
        else
        if n mod 6 = 0 then
        writeln(f[30])
        else writeln(f[24+(n mod 6)]);
end.

Code mẫu của RR

#include <sstream>
#include <iomanip>
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <string>
#include <deque>
#include <complex>

#define FOR(i,a,b) for(int i=(a),_b=(b); i<=_b; i++)
#define FORD(i,a,b) for(int i=(a),_b=(b); i>=_b; i--)
#define REP(i,a) for(int i=0,_a=(a); i<_a; i++)
#define FORN(i,a,b) for(int i=(a),_b=(b);i<_b;i++)
#define DOWN(i,a,b) for(int i=a,_b=(b);i>=_b;i--)
#define SET(a,v) memset(a,v,sizeof(a))
#define sqr(x) ((x)*(x))
#define ll long long
#define F first
#define S second
#define PB push_back
#define MP make_pair

#define DEBUG(x) cout << #x << " = "; cout << x << endl;
#define PR(a,n) cout << #a << " = "; FOR(_,1,n) cout << a[_] << ' '; cout << endl;
#define PR0(a,n) cout << #a << " = "; REP(_,n) cout << a[_] << ' '; cout << endl;
using namespace std;

//Buffer reading
int INP,AM,REACHEOF;
#define BUFSIZE (1<<12)
char BUF[BUFSIZE+1], *inp=BUF;
#define GETCHAR(INP) { \
    if(!*inp) { \
        if (REACHEOF) return 0;\
        memset(BUF,0,sizeof BUF);\
        int inpzzz = fread(BUF,1,BUFSIZE,stdin);\
        if (inpzzz != BUFSIZE) REACHEOF = true;\
        inp=BUF; \
    } \
    INP=*inp++; \
}
#define DIG(a) (((a)>='0')&&((a)<='9'))
#define GN(j) { \
    AM=0;\
    GETCHAR(INP); while(!DIG(INP) && INP!='-') GETCHAR(INP);\
    if (INP=='-') {AM=1;GETCHAR(INP);} \
    j=INP-'0'; GETCHAR(INP); \
    while(DIG(INP)){j=10*j+(INP-'0');GETCHAR(INP);} \
    if (AM) j=-j;\
}
//End of buffer reading

const long double PI = acos((long double) -1.0);

long long save[111];

int main() {
    long long cur = 1;
    FOR(i,1,100) {
        if (i == 1) save[i] = 1;
        else {
            long long next = cur * 2;
            stringstream ss; ss << next;
            string tmp; ss >> tmp; sort(tmp.begin(), tmp.end());

            ss.clear();

            ss << tmp;
            ss >> next;

            cur = next;
        }
        save[i] = cur;
    }
    int n; 
    while (cin >> n) {
        if (n > 27) {
            n = n % 6 + 30;
        }
        cout << save[n] << endl;
    }
    return 0;
}

Code mẫu của hieult

#include <set>
#include <map>
#include <list>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <string>
#include <vector>
#include <cstdlib>
#include <cstring>
#include <sstream>
#include <iomanip>
#include <iostream>
#include <algorithm>

#include <ctime>
#include <deque>
#include <bitset>
#include <cctype>
#include <utility>
#include <cassert>

using namespace std;

typedef long long ll;
typedef double ld;
typedef unsigned int ui;
typedef unsigned long long ull;

#define Rep(i,n) for(int i = 0; i < (n); ++i)
#define Repd(i,n) for(int i = (n)-1; i >= 0; --i)
#define For(i,a,b) for(int i = (a); i <= (b); ++i)
#define Ford(i,a,b) for(int i = (a); i >= (b); --i)
#define Fit(i,v) for(__typeof((v).begin()) i = (v).begin(); i != (v).end(); ++i)
#define Fitd(i,v) for(__typeof((v).rbegin()) i = (v).rbegin(); i != (v).rend(); ++i)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define sz(a) ((int)(a).size())
#define all(a) (a).begin(), (a).end()
#define ms(a,x) memset(a, x, sizeof(a))

template<class F, class T> T convert(F a, int p = -1) { stringstream ss; if (p >= 0) ss << fixed << setprecision(p); ss << a; T r; ss >> r; return r; }
template<class T> T gcd(T a, T b) { T r; while (b != 0) { r = a % b; a = b; b = r; } return a; }
template<class T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
template<class T> T sqr(T x) { return x * x; }
template<class T> T cube(T x) { return x * x * x; }
template<class T> int getbit(T s, int i) { return (s >> i) & 1; }
template<class T> T onbit(T s, int i) { return s | (T(1) << i); }
template<class T> T offbit(T s, int i) { return s & (~(T(1) << i)); }
template<class T> int cntbit(T s) { return s == 0 ? 0 : cntbit(s >> 1) + (s & 1); }

typedef pair<int, int> II;

const double PI = acos(-1.0);
const double eps = 1e-9;

const int dr[] = {-1, 0, +1, 0};
const int dc[] = {0, +1, 0, -1};

const int inf = (int)1e9 + 5;
const ll linf = (ll)1e16 + 5;
const ll mod = (ll)1e9 + 7;
#define maxn 100005

ll f[maxn];

ll go(ll x){
    int a[30];
    ll res = 0;
    int run = 0;
    while(x > 0){
        a[run++] = x % 10;
        x /= 10;
    }
    sort(a, a + run);
    Rep(i, run) res = res * 10 + a[i];
    return res;
}

ll cal(ll x){
    ll t = x * 2;
    return go(t);
}

int n;

int main(){
//  freopen("in.txt", "r", stdin);
    f[1] = 1;
    For(i, 2, 100){
        f[i] = cal(f[i - 1]);
    }

    cin >> n;
    if(n < 100){
        cout << f[n];
        return 0;
    }

    int t = (n - 40) % 6 + 40;
    cout << f[t];

    return 0;
}

Code mẫu của skyvn97

#include<stdio.h>
long n;
long res[]={1,2,4,8,16,23,46,29,58,116,223,446,289,578,1156,1223,2446,2489,4789,5789,11578,12356,12247,24449};
long seq[]={48889,77789,155578,111356,122227,244445};
int main(void)
{
    scanf("%ld",&n);
    if (n<25) printf("%ld",res[n-1]);
    else printf("%ld",seq[(n-25)%6]);
    return 0;
}

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