Editorial for Phá đường


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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 <cstdio>
using namespace std;

int n,Q,damaged[100100],q[100100],ans[100100],d[100100],region;

int get(int x)
{
    return x==d[x]?x:d[x]=get(d[x]);
}

int main()
{
    int m,b[100100],c[100100];
    cin >> n >> m >> Q;
    region=n;
    for (int i=1;i<=n;i++) d[i]=i;
    for (int i=0;i<m;i++) scanf("%d%d",b+i,c+i);
    for (int i=0;i<Q;i++) scanf("%d",q+i), damaged[--q[i]]=1;

    for (int i=0;i<m;i++)
        if (!damaged[i])
        {
            int x=get(b[i]),y=get(c[i]);
            if (x!=y) region--, d[x]=y;
        }

    for (int i=Q-1;i>=0;i--)
    {
        ans[i]=region;
        int x=get(b[q[i]]),y=get(c[q[i]]);
        if (x!=y) region--, d[x]=y;
    }       

    for (int i=0;i<Q;i++) printf("%d\n",ans[i]); 
}

Code mẫu của happyboy99x

#include<bits/stdc++.h>
using namespace std;

const int N = 1e5, M = 1e5, Q = 1e5;
int p[N], d[Q], u[M], v[M], n, m, q, nset, res[Q];
bool del[M];

void enter() {
    cin >> n >> m >> q;
    for(int i = 0; i < m; ++i)
        cin >> u[i] >> v[i], --u[i], --v[i];
    for(int i = 0; i < q; ++i)
        cin >> d[i], del[--d[i]] = true;
}

void reset(int n) {for(int i = 0; i < n; ++i) p[i] = i; nset = n;}
int getset(int u) {return u == p[u] ? u : p[u] = getset(p[u]);}
void joint(int u, int v) {if(getset(u) != getset(v)) p[p[u]]=p[v], --nset;}

void solve() {
    reset(n);
    for(int i = 0; i < m; ++i) if(!del[i]) joint(u[i], v[i]);
    for(int i = q-1; i >= 0; --i) res[i] = nset, joint(u[d[i]], v[d[i]]);
    for(int i = 0; i < q; ++i) cout << res[i] << '\n';
}

int main() {
    ios::sync_with_stdio(false);
    enter();
    solve();
    return 0;
}

Code mẫu của ladpro98

{$MODE OBJFPC}
program QHROAD;
uses    math;
const   fi='';
        maxn=trunc(1e5)+9;
type    edge=record
                x,y:longint;
        end;
var     n,m,qq,i,j,x,y,scc:longint;
        e:array[1..maxn] of edge;
        q,res,lab:array[1..maxn] of longint;
        chk:array[1..maxn] of boolean;
        inp:text;

function root(u:longint):longint;
begin
        if lab[u]<=0 then exit(u);
        result:=root(lab[u]);
        lab[u]:=result;
end;

procedure union(u,v:longint);
begin
        if lab[u]<lab[v] then lab[v]:=u
        else begin
                if lab[u]=lab[v] then dec(lab[v]);
                lab[u]:=v;
        end;
end;

begin
        assign(inp,fi);reset(inp);
        readln(inp,n,m,qq);
        for i:=1 to m do readln(inp,e[i].x,e[i].y);
        for i:=1 to qq do readln(inp,q[i]);
        for i:=1 to qq do chk[q[i]]:=true;
        scc:=n;
        for i:=1 to m do if not chk[i] then begin
                x:=root(e[i].x);y:=root(e[i].y);
                if x<>y then begin
                        union(x,y);
                        dec(scc);
                end;
        end;
        for i:=qq downto 1 do begin
                res[i]:=scc;
                x:=root(e[q[i]].x);y:=root(e[q[i]].y);
                if x<>y then begin
                        union(x,y);
                        dec(scc);
                end;
        end;
        for i:=1 to qq do writeln(res[i]);
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);
const int MN = 100111;

int lab[MN], nReg, res[MN], eu[MN], ev[MN], query[MN], mark[MN];
int n, m, q;

int getRoot(int u) {
    if (lab[u] < 0) return u;
    return lab[u] = getRoot(lab[u]);
}

void merge(int u, int v) {
    u = getRoot(u); v = getRoot(v);
    if (u == v) return ;

    --nReg;

    int x = lab[u] + lab[v];
    if (lab[u] < lab[v]) {
        lab[u] = x;
        lab[v] = u;
    }
    else {
        lab[v] = x;
        lab[u] = v;
    }
}

void solve() {
    FOR(i,1,m) if (!mark[i]) {
        merge(eu[i], ev[i]);
    }

    FORD(i,q,1) {
        res[i] = nReg;
        int t = query[i];
        merge(eu[t], ev[t]);
    }

    FOR(i,1,q) printf("%d\n", res[i]);
}

int main() {
    while (scanf("%d%d%d", &n, &m, &q) == 3) {
        FOR(i,1,n) lab[i] = -1;
        nReg = n;

        FOR(i,1,m) {
            scanf("%d%d", &eu[i], &ev[i]);
        }

        memset(mark, 0, sizeof mark);

        FOR(i,1,q) {
            scanf("%d", &query[i]);
            mark[query[i]] = i;
        }

        solve();
    }
    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>

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-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 int mod = (ll) (1e9 + 7 + eps);
#define ok puts("ok")

#define maxn 200005

int n, m, from[maxn], to[maxn], q, id[maxn], flag[maxn], dad[maxn], kq[maxn];

int getdad(int x){
    if(dad[x] == x) return x;
    return dad[x] = getdad(dad[x]);
}

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

    ms(flag, 0);
    scanf("%d %d %d", &n, &m, &q);
    For(i, 1, n) dad[i] = i;
    For(i, 1, m) scanf("%d %d", &from[i], &to[i]);
    For(i, 1, q){
        scanf("%d", &id[i]);
        flag[id[i]] = 1;
    }

    int u, v, t;
    kq[q] = n;
    For(i, 1, m) if(!flag[i]){
        u = getdad(from[i]);
        v = getdad(to[i]);
        if(u != v){
            kq[q]--;
            if(u > v) swap(u, v);
            dad[v] = u;
        }
    }

    Ford(i, q, 2){
        kq[i - 1] = kq[i];
        t = id[i];
        u = getdad(from[t]);
        v = getdad(to[t]);
        if(u != v){
            kq[i - 1]--;
            if(u > v) swap(u, v);
            dad[v] = u;
        }
    }

    For(i, 1, q) printf("%d\n", kq[i]);

    return 0;
}

Code mẫu của skyvn97

program qhroad;
uses crt;
const
        max=100100;
type
        edge=record
                u,v:longint;
                isq:boolean;
        end;
var
        a:array[1..max] of edge;
        up:array[1..max] of longint;
        qr:array[1..max] of longint;
        res:array[1..max] of longint;
        m,n,q,cp:longint;
function find(x:integer):integer;
        begin
                if up[x]<0 then exit(x);
                up[x]:=find(up[x]);
                exit(up[x]);
        end;
function join(a,b:integer):integer;
        var
                x,y:integer;
        begin
                x:=find(a);
                y:=find(b);
                if x=y then exit(0);
                up[y]:=x;
                exit(1);
        end;
procedure loadgraph;
        var
                i:longint;
        begin
                read(n);
                read(m);
                read(q);
                for i:=1 to n do up[i]:=-1;
                for i:=1 to m do
                        begin
                                read(a[i].u);
                                read(a[i].v);
                                a[i].isq:=false;
                        end;
                for i:=1 to q do
                        begin
                                read(qr[i]);
                                a[qr[i]].isq:=true;
                        end;
                cp:=n;
        end;
procedure process;
        var
                i:integer;
        begin
                for i:=1 to m do
                        if not a[i].isq then cp:=cp-join(a[i].u,a[i].v);
                for i:=q downto 1 do
                        begin
                                res[i]:=cp;
                                cp:=cp-join(a[qr[i]].u,a[qr[i]].v);
                        end;
                for i:=1 to q do writeln(res[i]);
        end;
begin
//        assign(input,'tmp.txt'); reset(input);
        loadgraph;
        process;
end.

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