Submission #228838

#	Time	Username	Problem	Language	Result	Execution time	Memory
228838		rqi	Port Facility (JOI17_port_facility)	C++14	100 / 100	1061 ms	187224 KiB

port_facility

#include <bits/stdc++.h>
using namespace std;
 
typedef long long ll;
typedef long double ld;
typedef double db; 
typedef string str; 

typedef pair<int,int> pi;
typedef pair<ll,ll> pl; 
typedef pair<db,db> pd; 

typedef vector<int> vi; 
typedef vector<ll> vl; 
typedef vector<db> vd; 
typedef vector<str> vs; 
typedef vector<pi> vpi;
typedef vector<pl> vpl; 
typedef vector<pd> vpd; 

#define mp make_pair 
#define f first
#define s second
#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rall(x) (x).rbegin(), (x).rend() 
#define rsz resize
#define ins insert 
#define ft front() 
#define bk back()
#define pf push_front 
#define pb push_back
#define eb emplace_back 
#define lb lower_bound 
#define ub upper_bound 

#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)

const int MOD = 1e9+7; // 998244353;
const int MX = 2e5+5; 
const ll INF = 1e18; 
const ld PI = acos((ld)-1);
const int xd[4] = {1,0,-1,0}, yd[4] = {0,1,0,-1}; 

template<class T> bool ckmin(T& a, const T& b) { 
    return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { 
    return a < b ? a = b, 1 : 0; } 
int pct(int x) { return __builtin_popcount(x); } 
int bit(int x) { return 31-__builtin_clz(x); } // floor(log2(x)) 
int cdiv(int a, int b) { return a/b+!(a<0||a%b == 0); } // division of a by b rounded up, assumes b > 0 

// INPUT
template<class A> void re(complex<A>& c);
template<class A, class B> void re(pair<A,B>& p);
template<class A> void re(vector<A>& v);
template<class A, size_t SZ> void re(array<A,SZ>& a);

template<class T> void re(T& x) { cin >> x; }
void re(db& d) { str t; re(t); d = stod(t); }
void re(ld& d) { str t; re(t); d = stold(t); }
template<class H, class... T> void re(H& h, T&... t) { re(h); re(t...); }

template<class A> void re(complex<A>& c) { A a,b; re(a,b); c = {a,b}; }
template<class A, class B> void re(pair<A,B>& p) { re(p.f,p.s); }
template<class A> void re(vector<A>& x) { trav(a,x) re(a); }
template<class A, size_t SZ> void re(array<A,SZ>& x) { trav(a,x) re(a); }

// TO_STRING
#define ts to_string
template<class A, class B> str ts(pair<A,B> p);
template<class A> str ts(complex<A> c) { return ts(mp(c.real(),c.imag())); }
str ts(bool b) { return b ? "true" : "false"; }
str ts(char c) { str s = ""; s += c; return s; }
str ts(str s) { return s; }
str ts(const char* s) { return (str)s; }
str ts(vector<bool> v) { 
    bool fst = 1; str res = "{";
    F0R(i,sz(v)) {
        if (!fst) res += ", ";
        fst = 0; res += ts(v[i]);
    }
    res += "}"; return res;
}
template<size_t SZ> str ts(bitset<SZ> b) {
    str res = ""; F0R(i,SZ) res += char('0'+b[i]);
    return res; }
template<class T> str ts(T v) {
    bool fst = 1; str res = "{";
    for (const auto& x: v) {
        if (!fst) res += ", ";
        fst = 0; res += ts(x);
    }
    res += "}"; return res;
}
template<class A, class B> str ts(pair<A,B> p) {
    return "("+ts(p.f)+", "+ts(p.s)+")"; }

// OUTPUT
template<class A> void pr(A x) { cout << ts(x); }
template<class H, class... T> void pr(const H& h, const T&... t) { 
    pr(h); pr(t...); }
void ps() { pr("\n"); } // print w/ spaces
template<class H, class... T> void ps(const H& h, const T&... t) { 
    pr(h); if (sizeof...(t)) pr(" "); ps(t...); }

// DEBUG
void DBG() { cerr << "]" << endl; }
template<class H, class... T> void DBG(H h, T... t) {
    cerr << to_string(h); if (sizeof...(t)) cerr << ", ";
    DBG(t...); }
#ifdef LOCAL // compile with -DLOCAL
#define dbg(...) cerr << "[" << #__VA_ARGS__ << "]: [", DBG(__VA_ARGS__)
#else
#define dbg(...) 42
#endif

// FILE I/O
void setIn(string s) { freopen(s.c_str(),"r",stdin); }
void setOut(string s) { freopen(s.c_str(),"w",stdout); }
void unsyncIO() { ios_base::sync_with_stdio(0); cin.tie(0); }
void setIO(string s = "") {
    unsyncIO();
    // cin.exceptions(cin.failbit); 
    // throws exception when do smth illegal
    // ex. try to read letter into int
    if (sz(s)) { setIn(s+".in"), setOut(s+".out"); } // for USACO
}

mt19937 rng((uint32_t)chrono::steady_clock::now().time_since_epoch().count()); 


const int mx = 1000005;
int N;
int A[mx];
int B[mx];
int val[mx];
vi adj[mx];
priority_queue<pi, vector<pi>, greater<pi>> Bvals[mx];
priority_queue<pi, vector<pi>, greater<pi>> minBvals;

/**
 * Description: Disjoint Set Union with path compression. 
     * Add edges and test connectivity. Use for Kruskal's 
     * minimum spanning tree.
 * Time: O(\alpha(N))
 * Source: CSAcademy, KACTL
 * Verification: USACO superbull
 */

struct DSU {
    vi e; void init(int n) { e = vi(n,-1); }
    int get(int x) { return e[x] < 0 ? x : e[x] = get(e[x]); } 
    bool sameSet(int a, int b) { return get(a) == get(b); }
    int size(int x) { return -e[get(x)]; }
    bool unite(int x, int y) { // union-by-rank
        x = get(x), y = get(y); if (x == y) return 0;
        if (e[x] > e[y]) swap(x,y);
        e[x] += e[y]; e[y] = x; return 1;
    }
};


DSU dsu;

/**template<class T> T kruskal(int n, vector<pair<T,pi>> ed) {
    sort(all(ed));
    T ans = 0; DSU D; D.init(n+1); // edges that unite are in MST
    trav(a,ed) if (D.unite(a.s.f,a.s.s)) ans += a.f; 
    return ans;
}*/





void addEdge(int a, int b){
    adj[a].pb(b);
    adj[b].pb(a);
    dsu.unite(a, b);
    //dbg(a, b);
}

void search(int node, int c){
    if(val[node] != 2){
        return;
    }
    val[node] = c;
    for(auto u: adj[node]){
        search(u, 1-c);
    }
}

void genPrelim(){
    for(int i = 1; i <= N; i++){
        val[i] = 2;
    }
    for(int i = 1; i <= N; i++){
        if(val[i] != 2) continue;
        search(i, 0);
    }
}

int main() {
    setIO();
    
    cin >> N;
    dsu.init(N+5);
    vpi inters;
    for(int i = 1; i <= N; i++){
        int a, b;
        cin >> a >> b;
        inters.pb(mp(a, b));
    }
    sort(all(inters));
    for(int i = 1; i <= N; i++){
        A[i] = inters[i-1].f;
        B[i] = inters[i-1].s;
    }

    for(int i = 1; i <= N; i++){
        //first, remove all unnecessary values from the front
        while(sz(minBvals)){
            pi a = minBvals.top();
            if(a.f > A[i]){
                //all work
                break;
            }
            minBvals.pop();
            Bvals[a.s].pop();
            if(sz(Bvals[a.s])){
                minBvals.push(mp(Bvals[a.s].top().f, a.s));
            }
        }
        //next, find out all components that need to be merged    
        vi conec; //components you will need to unite to
        while(sz(minBvals)){
            pi a = minBvals.top();
            if(a.f > B[i]) break;
            minBvals.pop();
            int intind = Bvals[a.s].top().s;
            addEdge(i, intind);
            conec.pb(a.s);
        }   
        
        //insert B[i]
        
        Bvals[i].push(mp(B[i], i));
        conec.pb(i);
        //merge the components in conec
        int comp = i;
        for(auto u: conec){
            if(sz(Bvals[u]) > sz(Bvals[comp])) comp = u;
        }
        for(auto u: conec){
            if(u == comp) continue;
            while(sz(Bvals[u])){
                pi a = Bvals[u].top();
                Bvals[u].pop();
                Bvals[comp].push(a);
            }
        }
        //edit minbvals
        minBvals.push(mp(Bvals[comp].top().f, comp));  
    }

    genPrelim(); //assigns 0 or 1 to each interval
    /*for(int i = 1; i <= N; i++){
        ps(val[i]);
    }*/
    priority_queue<int, vector<int>, greater<int>> q[2]; //0/1, position of B
    for(int i = 1; i <= N; i++){
        //remove unnecessary stuff
        while(sz(q[val[i]])){
            int pos = q[val[i]].top();
            if(pos > A[i]) break;
            q[val[i]].pop();
        }
        //test if it contradicts
        if(sz(q[val[i]])){
            int pos = q[val[i]].top();
            if(pos < B[i]){
                ps(0);
                return 0;
            }
        }
        //add to the right queue
        q[val[i]].push(B[i]);
    }
    ll ans = 1;
    for(int i = 1; i <= N; i++){
        if(dsu.e[i] < 0){
            ans = (ans*2) % MOD;
        }
    }
    ps(ans);
    // you should actually read the stuff at the bottom
}

/* stuff you should look for
    * int overflow, array bounds
    * special cases (n=1?)
    * do smth instead of nothing and stay organized
    * WRITE STUFF DOWN
*/

Compilation message (stderr)

port_facility.cpp: In function 'void setIn(std::__cxx11::string)':
port_facility.cpp:123:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
 void setIn(string s) { freopen(s.c_str(),"r",stdin); }
                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
port_facility.cpp: In function 'void setOut(std::__cxx11::string)':
port_facility.cpp:124:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
 void setOut(string s) { freopen(s.c_str(),"w",stdout); }
                         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 56 / 56
• Subtask 4: 22 / 22