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

const maxn=1048575;
var n,k,num,s,f:longint;
    p:array[0..20] of longint;
    q,d:array[1..maxn] of longint;
    a:array[1..20] of longint;

procedure rf;
var i,x,j,y:longint;
begin
     read(n,k);
     p[0]:=1;
     for i:=1 to n do p[i]:=p[i-1] shl 1;
     f:=p[k-1];
     for i:=1 to n do
     begin
          read(x);
          for j:=1 to x do
          begin
               read(y);
               a[i]:=a[i] or p[y-1];
          end;
          a[i]:=p[n]-1-a[i];
     end;
     for i:=1 to n do
     begin
          read(x);
          if x=1 then
             s:=s or p[i-1];
     end;
end;

procedure pr;
var i,j,x:longint;
begin
     num:=1; i:=1; d[s]:=1; q[1]:=s;
     repeat
           for j:=1 to n do
           begin
                x:=(q[i] and a[j]) or p[j-1];
                if d[x]=0 then
                begin
                     d[x]:=d[q[i]]+1;
                     if x=f then exit;
                     inc(num);
                     q[num]:=x;
                end;
           end;
           inc(i);
     until (d[f]<>0) or (i>num);
end;

procedure wf;
begin
     if d[f]=0 then writeln(-1)
     else writeln(d[f]-1);
end;

begin
     rf;
     pr;
     wf;
end.

Code mẫu của happyboy99x

#include<cstdio>
#include<queue>
using namespace std;

int n, k, a[30], start;
bool check[1<<20];

void enter() {
    scanf("%d%d",&n,&k); k = 1 << (k-1); 
    for(int i = 0; i < n; ++i) {
        int s; scanf("%d", &s);
        a[i] = -1;
        for(int j = 0; j < s; ++j) {
            int t; scanf("%d",&t);
            a[i] &= ~(1 << (t-1));
        }
    }
    start = 0;
    for(int i = 0; i < n; ++i) {
        int t; scanf("%d",&t);
        if(t) start |= 1 << i;
    }
}

void solve() {
    queue<int> qu; qu.push(start); check[start] = 1;
    for(int step = 0; !qu.empty(); ++step) 
    for(int Z = qu.size()-1; Z >= 0; --Z) {
        int state = qu.front(); qu.pop();
        if(state == k) {
            printf("%d\n", step); return;
        }
        for(int i = 0; i < n; ++i) {
            int newState = (state & a[i]) | (1 << i);
            if(!check[newState]) {
                check[newState] = 1;
                qu.push(newState);
            }
        }
    }
    printf("-1\n");
}

int main() {
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
#endif
    enter();
    solve();
}

Code mẫu của ladpro98

program lem2;
uses    math;
const   maxn=20;
        fi='';
var     press,t:array[1..maxn] of longint;
        d,q:array[0..1 shl maxn] of longint;
        check:array[0..1 shl maxn] of boolean;
        start,n,target,k:longint;

procedure input;
var     inp:text;
        i,s,j,p:longint;
begin
        assign(inp,fi);reset(inp);
        readln(inp,n,k);
        target:=1 shl (k-1);
        for i:=1 to n do
        begin
                read(inp,s);
                press[i]:=1 shl n-1;
                for j:=1 to s do
                begin
                        read(inp,p);
                        dec(press[i],1 shl (p-1));
                end;
                readln(inp);
        end;
        for i:=1 to n do read(inp,t[i]);
        for i:=n downto 1 do start:=2*start+t[i];
        close(inp);
end;

function getbit(i,j:longint):longint;
begin
        exit(i shr (j-1) and 1);
end;

procedure bfs;
var     l,r,u,v,i:longint;
begin
        l:=1;r:=1;
        q[1]:=start;
        check[start]:=true;
        d[start]:=0;
        while l<=r do
        begin
                u:=q[l];inc(l);
                for i:=1 to n do
                begin
                        v:=u and press[i];
                        if getbit(v,i)=0 then
                        v:=v+1 shl (i-1);

                        if not check[v] then
                        begin
                                check[v]:=true;
                                inc(r);
                                q[r]:=v;
                                d[v]:=d[u]+1;
                                if v=target then
                                begin
                                        write(d[v]);
                                        halt;
                                end;
                        end;
                end;
        end;
end;

begin
        input;
        bfs;
        write(-1);
end.

Code mẫu của RR

{$R-,Q-}
const
  FINP='';
  FOUT='';
  MAXN=20;
  oo=1000000;
var
  first,last,k,n:longint;
  a:array[1..MAXN] of longint;
  queue,d:array[0..1048577] of longint;
procedure inp; inline;
var
  f:text;
  i,j,jj,x:longint;
begin
  assign(f,FINP); reset(f);
  read(f,n,k);
  for i:=1 to n do
    begin
      read(f,j);
      for jj:=1 to j do
        begin
          read(f,x);
          if (a[i] shr (x-1)) and 1=0 then a[i]:=a[i]+1 shl (x-1);
        end;
      a[i]:=not a[i];
    end;
  j:=0;
  for i:=1 to n do
    begin
      read(f,x);
      if x=1 then j:=j+1 shl (i-1);
    end;
  for i:=1 shl n downto 0 do d[i]:=oo;
  first:=1; last:=1; queue[1]:=j;
  d[j]:=0;
  close(f);
end;
procedure solve; inline;
var
  u,i,uu:longint;
begin
  while first<=last do
    begin
      u:=queue[first]; inc(first);
      for i:=1 to n do
        begin
          uu:=(u or (1 shl (i-1))) and a[i];
          if d[uu]=oo then
            begin
              d[uu]:=d[u]+1;
              inc(last); queue[last]:=uu;
              if uu=1 shl (k-1) then exit;
            end;
        end;
    end;
end;
procedure ans; inline;
var
  f:text;
begin
  assign(f,FOUT); rewrite(f);
  if d[1 shl (k-1)]<oo then writeln(f,d[1 shl (k-1)])
  else writeln(f,-1);
  close(f);
end;
begin
  inp;
  solve;
  ans;
end.

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>

using namespace std;

typedef long long ll;
typedef long 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);
}

const int bfsz = 1 << 16;
char bf[bfsz + 5];
int rsz = 0;
int ptr = 0;
char gc() {
    if (rsz <= 0) {
        ptr = 0;
        rsz = (int) fread(bf, 1, bfsz, stdin);
        if (rsz <= 0)
            return EOF;
    }
    --rsz;
    return bf[ptr++];
}
void ga(char &c) {
    c = EOF;
    while (!isalpha(c))
        c = gc();
}
int gs(char s[]) {
    int l = 0;
    char c = gc();
    while (isspace(c))
        c = gc();
    while (c != EOF && !isspace(c)) {
        s[l++] = c;
        c = gc();
    }
    s[l] = '\0';
    return l;
}
template<class T> bool gi(T &v) {
    v = 0;
    char c = gc();
    while (c != EOF && c != '-' && !isdigit(c))
        c = gc();
    if (c == EOF)
        return false;
    bool neg = c == '-';
    if (neg)
        c = gc();
    while (isdigit(c)) {
        v = v * 10 + c - '0';
        c = gc();
    }
    if (neg)
        v = -v;
    return true;
}

typedef pair<int, int> II;
const ld PI = acos(-1.0);
const ld eps = 1e-12;
const int dr[] = { -1, 0, +1, 0};
const int dc[] = { 0, +1, 0, -1};
const int inf = (int) 1e9 + 5;
const ll linf = (ll) 1e18 + 5;
const int mod = (ll) (1e9 + eps);

using namespace std;

#define maxn 21

int n, k, d[21], f[1 << 21], que[1 << 21];

int main(){
//  freopen("in.txt", "r", stdin);

    cin >> n >> k;
    k--;

    int num, x, u, A = 0;
    ms(d, 0); ms(f, 0x3f);
    Rep(i, n){
        cin >> num;
        Rep(run, num){
            cin >> x;
            x--;
            d[i] += (1 << x);
        }
    }

    Rep(i, n) {
        cin >> x;
        if(x) A += (1 << i);
    }

    f[A] = 0;
    int size = 0;
    que[size++] = A;
    Rep(i, size){
        u = que[i];
        if(u == (1 << k)) break;
        Rep(j, n) {
            A = onbit((u & d[j]) ^ u, j);
            if(f[A] > f[u] + 1){
                f[A] = f[u] + 1;
                que[size++] = A;
            }
        }
    }

    if(f[1 << k] < inf) cout << f[1 << k];
    else cout << -1;

    return 0;
}

Code mẫu của ll931110

{$MODE DELPHI}
Program LEM2;
Const
  input  = '';
  output = '';
  maxn = 20;
  maxd = 2200000;
Var
  n,k: integer;
  start,finish: integer;
  d,queue: array[0..maxd] of integer;
  s: array[1..maxn] of integer;

Procedure init;
Var
  f: text;
  a,i,j,t: integer;
Begin
  Assign(f, input);
    Reset(f);

  Readln(f, n, k);
  For i:= 1 to n do
    Begin
     Read(f, a);
     s[i]:= 0;
     For j:= 1 to a do
       Begin
         Read(f, t);
         s[i]:= s[i] + 1 shl (t - 1);
       End;
    End;

  finish:= 1 shl (k - 1);
  start:= 0;
  For i:= 1 to n do
    Begin
      Read(f, t);
      If t = 1 then start:= start + 1 shl (i - 1);
    End;

  Close(f);
End;

Procedure BFS;
Var
  front,rear: integer;
  u,v,i: integer;
Begin
  If start = finish then
    Begin
      d[start]:= 0;
      exit;
    End;

  Fillchar(d, sizeof(d), 0);
  d[start]:= 0;

  front:= 1;
  rear:= 1;
  queue[1]:= start;

  Repeat
    u:= queue[front];
    inc(front);

    For i:= 1 to n do
      Begin
        v:= (u or (1 shl (i - 1))) and (not s[i]);
        If (d[v] = 0) and (v <> start) then
          Begin
            d[v]:= d[u] + 1;
            If v = finish then exit;
            inc(rear);
            queue[rear]:= v;
          End;
      End;
  Until front > rear;
End;

Procedure printresult;
Var
  f: text;
Begin
  Assign(f, output);
    Rewrite(f);
    If (d[finish] = 0) and (finish <> start)
      then writeln(f, -1) else writeln(f, d[finish]);
  Close(f);
End;

Begin
  init;
  BFS;
  printresult;
End.

Code mẫu của skyvn97

#include<cstdio>
#include<cstring>
#include<queue>
#define FOR(i,a,b) for (int i=(a),_b=(b);i<=_b;i=i+1)
#define REP(i,n) for (int i=0,_n=(n);i<_n;i=i+1)
#define MASK(i) (1<<(i))
using namespace std;
int dis[MASK(20)+7];
int stt[22];
int n,goal,sta;
int nextInt(void) {
    int x;
    scanf("%d",&x);
    return (x);
}
void init(void) {
    n=nextInt();
    goal=MASK(nextInt()-1);
    REP(i,n) REP(zz,nextInt()) stt[i]|=MASK(nextInt()-1);
    REP(i,n) if (nextInt()==1) sta|=MASK(i);
}
void bfs(void) {
    memset(dis,-1,sizeof dis);
    queue<int> q;
    dis[sta]=0;
    q.push(sta);
    while (!q.empty()) {
        int u=q.front();q.pop();
        if (u==goal) {
            printf("%d\n",dis[u]);
            return;
        }
        REP(i,n) {
            int v=(u|MASK(i))&~stt[i];
            if (dis[v]<0) {
                dis[v]=dis[u]+1;
                q.push(v);
            }
        }
    }
    printf("-1\n");
}
int main(void) {
    init();
    bfs();
    return 0;
}