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

Code mẫu của happyboy99x

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

#define TR(v,it) for(typeof((v).begin())it=(v).begin();it!=(v).end();++it)
vector<vector<int> > g;
int n, m, p;
bool vst[30000];

int main() {
    scanf("%d%d%d",&n,&m,&p);
    g.resize(n);
    for(int i = 0; i < m; ++i) {
        int u, v; scanf("%d%d",&u,&v);
        g[--u].push_back(--v);
        g[v].push_back(u);
    }
    for(int i = 0; i < p; ++i) {
        int u; scanf("%d", &u);
        vst[--u] = 1;
        TR(g[u], it) {
            vst[*it] = 1;
        }
    }
    queue<int> qu; qu.push(0); int res = n; vst[0] = 1;
    while(!qu.empty()) {
        --res; int u = qu.front(); qu.pop();
        TR(g[u], it) if(!vst[*it]) {
            vst[*it] = 1;
            qu.push(*it);
        }
    }
    printf("%d\n", res);
    return 0;
}

Code mẫu của ladpro98

#include <cstring>
#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <climits>
#include <cstdlib>
#include <ctime>
#include <memory.h>
#include <cassert>
#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define REP(i, a, b) for(int i = (a); i <=(b); i++)
#define FORD(i, a, b) for(int i = (a); i > (b); i--)
#define REPD(i, a, b) for(int i = (a); i >=(b); i--)
#define TR(it, a) for(typeof((a).begin()) it = (a).begin(); it != (a).end(); ++it)
#define RESET(a, v) memset((a), (v), sizeof((a)))
#define SZ(a) (int((a).size()))
#define ALL(a) (a).begin(), (a).end()
#define PB push_back
#define MP make_pair
#define LL long long
#define LD long double
#define II pair<int, int>
#define X first
#define Y second
#define VI vector<int>
const int N = 30006;
using namespace std;
int n, m, q, ans;
VI a[N];
bool damaged[N], was[N];

void dfs(int u) {
    ans -= (was[u] = 1);
    TR(v, a[u])
    if (!damaged[*v] && !was[*v])
        dfs(*v);
}

int main() {
    ios :: sync_with_stdio(0); cin.tie(0);
    cin >> n >> m >> q;
    int u, v;
    FOR(i, 0, m) {
        cin >> u >> v;
        a[u].PB(v); a[v].PB(u);
    }
    while (q--) {
        cin >> u;
        TR(v, a[u]) damaged[*v] = 1;
    }
    ans = n;
    dfs(1);
    cout << ans;
    return 0;
}

Code mẫu của RR

{
PROG: damage
LANG: PASCAL
ID: invinci3
}
const
  FINP='';
  FOUT='';
  MAXN=30001;
type
  list=^node;
  node=record
         u:longint;
         next:list;
       end;
var
  f1,f2:text;
  q,n:longint;
  xet,c,dd:array[1..MAXN] of longint;
  ke:array[1..MAXN] of list;
procedure openF;
begin
  assign(f1,FINP); reset(f1);
  assign(f2,FOUT); rewrite(f2);
end;
procedure closeF;
begin
  close(f1); close(f2);
end;
procedure add(u:longint; var a:list);
var
  p:list;
begin
  new(p); p^.u:=u;
  p^.next:=a; a:=p;
end;
procedure inp;
var
  i,u,v,m:longint;
begin
  read(f1,n,m,q);
  for i:=1 to m do
    begin
      read(f1,u,v);
      add(u,ke[v]);
      add(v,ke[u]);
    end;
  for i:=1 to q do
    begin
      read(f1,u);
      dd[u]:=-1;
    end;
end;
procedure dfs(u:longint);
var
  v:longint;
  p:list;
begin
  c[u]:=1;
  p:=ke[u]; xet[u]:=1;
  while p<>nil do
    begin
      v:=p^.u; p:=p^.next;
      if xet[v]=1 then continue;
      if dd[v]=0 then dfs(v);
    end;
end;
procedure solve;
var
  v,u:longint;
  p:list;
begin
  for u:=1 to n do
  if dd[u]=-1 then
    begin
      p:=ke[u];
      while p<>nil do
        begin
          v:=p^.u; p:=p^.next;
          if dd[v]=0 then dd[v]:=1;
        end;
    end;
  if dd[1]=0 then dfs(1);
end;
procedure ans;
var
  i,count:longint;
begin
  count:=0;
  for i:=2 to n do inc(count,c[i]);
  writeln(f2,n-1-count);
end;
begin
  openF;
  inp;
  solve;
  ans;
  closeF;
end.

Code mẫu của hieult

#include <set>
#include <map>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <bitset>
#include <cctype>
#include <cstdio>
#include <string>
#include <vector>
#include <cassert>
#include <cstdlib>
#include <cstring>
#include <sstream>
#include <iomanip>
#include <iostream>
#include <algorithm>

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(__typeof(n) i = 0; i < (n); ++i)
#define Repd(i,n) for(__typeof(n) i = (n)-1; i >= 0; --i)
#define For(i,a,b) for(__typeof(b) i = (a); i <= (b); ++i)
#define Ford(i,a,b) for(__typeof(a) 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))
#define nl puts("")
#define sp printf(" ")
#define ok puts("ok")
//#include <conio.h>

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> void db(T a, int p = -1) { if (p >= 0) cout << fixed << setprecision(p); cout << a << " "; }
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> struct Triple { T x, y, z; Triple() {} Triple(T _x, T _y, T _z) : x(_x), y(_y), z(_z) {} };
template<class T> Triple<T> euclid(T a, T b) { if (b == 0) return Triple<T>(1, 0, a); Triple<T> r = euclid(b, a % b); return Triple<T>(r.y, r.x - a / b * r.y, r.z); }
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 = 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;
}

const double PI = 2 * acos(0);
const string months[] = {"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"};
const int days[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
//const int dr[] = {0, 0, -1, +1};
//const int dc[] = {-1, +1, 0, 0};
const int dr[] = {-2, -1, +1, +2, +2, +1, -1, -2};
const int dc[] = {+1, +2, +2, +1, -1, -2, -2, -1};

const int inf = (int)1e9 + 5;
const ll linf = (ll)1e16 + 5;
const double eps = 1e-9;
const ll mod = 1000000000;
typedef pair<int, int> II;

using namespace std;

#define maxn 30005
#define maxe 200005

int n, m, p;
int adj[maxe], next[maxe], last[maxn], E = 0, a[maxn], que[maxn];
bool flag[maxn] = {0};

void add(int u, int v){
    adj[E] = v; next[E] = last[u]; last[u] = E++;
    adj[E] = u; next[E] = last[v]; last[v] = E++;
}

int go(){
    if(a[1]) return 0;
    flag[1] = 1;
    int size = 0; que[size++] = 1;
    int u, v;
    Rep(i, size){
        u = que[i];
        for(int e = last[u]; e != -1; e = next[e]){
            v = adj[e];
            if(!flag[v] && !a[v]){
                flag[v] = 1;
                que[size++] = v;
            }
        }
    }
    return size;

}

int main(){

//    freopen("in.txt","r",stdin);
//    freopen("out.txt","w",stdout);
    int u, v;
    gi(n); gi(m); gi(p);
    ms(last, -1); ms(a, 0);
    Rep(i, m){
        gi(u); gi(v); add(u, v);
    }

    Rep(i, p){
        gi(u);
        a[u] = 1;
        for(int e = last[u]; e != -1; e = next[e]){
            v = adj[e];
            a[v] = 1;
        }
    }
    printf("%d", n - go());
     // getch();
}

Code mẫu của ll931110

program DAMAGE;
const
  input  = '';
  output = '';
  maxn = 30000 + 40;
type
  pnode = ^tnode;
  tnode = record
    val: longint;
    link: pnode;
  end;
var
  fi,fo: text;
  n,m,q: longint;
  a: array[1..maxn] of pnode;
  free,path: array[1..maxn] of boolean;

procedure openfile;
begin
  assign(fi, input);  reset(fi);
  assign(fo, output);  rewrite(fo);
end;

procedure closefile;
begin
  close(fo);
  close(fi);
end;

procedure add(u,v: longint);
var
  p: pnode;
begin
  new(p);
  p^.val := v;
  p^.link := a[u];
  a[u] := p;
end;

procedure init;
var
  i,u,v: longint;
begin
  readln(fi, n, m, q);
  for i := 1 to m do
    begin
      readln(fi, u, v);
      add(u,v);  add(v,u);
    end;
end;

procedure DFS(u: longint);
var
  p: pnode;
begin
  path[u] := true;
  p := a[u];
  while p <> nil do
    begin
      if not path[p^.val] and free[p^.val] then DFS(p^.val);
      p := p^.link;
    end;
end;

procedure solve;
var
  i,x,cc: longint;
  p: pnode;
begin
  cc := 0;
  fillchar(path, sizeof(path), false);
  fillchar(free, sizeof(free), true);

  for i := 1 to q do
    begin
      readln(fi, x);
      if free[x] then free[x] := false;

      p := a[x];
      while p <> nil do
        begin
          if free[p^.val] then free[p^.val] := false;
          p := p^.link;
        end;
    end;

  DFS(1);
  for i := 1 to n do
    if not free[i] or not path[i] then inc(cc);
  writeln(fo, cc);
end;

begin
  openfile;
  init;
  solve;
  closefile;
end.