Submission #205857

#	Time	Username	Problem	Language	Result	Execution time	Memory
205857		jh05013	절취선 (JOI14_ho_t5)	C++17	100 / 100	322 ms	14460 KiB

2014_ho_t5

#include <bits/stdc++.h>
#define sz(X) (int)((X).size())
#define entire(X) X.begin(),X.end()
using namespace std; typedef long long ll;
void OJize(){cin.tie(NULL);ios_base::sync_with_stdio(false);}
template <class T1, class T2>ostream&operator<<(ostream &os,pair<T1,T2>const&x){os<<'('<<x.first<<", "<<x.second<<')';return os;}
template <class Ch, class Tr, class Container>basic_ostream<Ch,Tr>&operator<<(basic_ostream<Ch,Tr>&os,Container const&x){for(auto&y:x)os<<y<<" ";return os;}

template <typename T>
struct Compress{
    int n; vector<T> arr;
    void add(T x){arr.push_back(x); n++;}
    void init(){sort(entire(arr)), 
        arr.erase(unique(entire(arr)), arr.end()), n=arr.size();}
    int lb(T x){return lower_bound(entire(arr), x) - arr.begin();}
};

struct DisjointSet{
    vector<int> par;
    DisjointSet(int n): par(n) {iota(entire(par), 0);}
    void un(int x, int y){par[fd(x)] = fd(y);} // yr becomes parent
    int fd(int x){return par[x]!=x? (par[x]=fd(par[x])):x;}
};

template <typename T>
struct Fenwick{
    int n; vector<T> arr;
    Fenwick(int N): n{N}, arr(N) {}
    void add(int i, T val){
        while(i < n) arr[i]+= val, i |= i+1;
    }
    T getsum(int i){
        T res = 0;
        while(i >= 0) res+= arr[i], i = (i&(i+1))-1;
        return res;
    }
    T intersum(int i, int j){
        if(j < i) return 0;
        return i? (getsum(j) - getsum(i-1)) : getsum(j);
    }
};

set<int> vert;
int side(int x, bool left){
    auto it = vert.lower_bound(x);
    return left? *(--it) : *(++it);
}
bool contains(int l, int r){
    return vert.lower_bound(l) != vert.upper_bound(r);
}

int main(){OJize();
    int w,h,n; cin>>w>>h>>n;
    vector<tuple<int,int,int,int,int>> ev; // y, type, l, r, idx
    Compress<int> C;
    C.add(0), C.add(w);
    // type 1 = vertical start (uses l=r)
    // type 2 = horizontal (uses l, r)
    // type 3 = vertical end (uses l=r)
    for(int i=0; i<n; i++){
        int xa,ya,xb,yb; cin>>xa>>ya>>xb>>yb;
        C.add(xa), C.add(xb);
        if(xa == xb){
            ev.push_back({ya, 1, xa, xb, i});
            ev.push_back({yb, 3, xa, xb, i});
        }
        else ev.push_back({ya, 2, xa, xb, i});
    }
    ev.push_back({0,2,0,w,n}), ev.push_back({h,2,0,w,n+1});
    ev.push_back({0,1,0,0,n+2}), ev.push_back({0,1,w,w,n+3});
    ev.push_back({h,3,0,0,n+2}), ev.push_back({h,3,w,w,n+3});
    C.init(), sort(entire(ev));
    Fenwick<int> F(sz(C.arr));

    // count V and E
    ll V=0, E=0, COMP=0;
    for(auto [y,ty,x1,x2,_]: ev){
        x1 = C.lb(x1), x2 = C.lb(x2);
        if(ty == 1) F.add(x1, 1), V++;
        else if(ty == 2){
            ll ic = F.intersum(x1, x2);
            V+= ic+2, E+= 2*ic+1;
        }
        else if(ty == 3) F.add(x1, -1), V++, E++;
    }

    // count COMP
    DisjointSet DS(n+4);
    COMP = 0;
    map<int, pair<int,int>> area; // {s, {e, idx}}
    area[-2] = {-1, -1}, area[w+1] = {w+2, -1};
    for(auto [y,ty,x1,x2,idx]: ev){
        x1 = C.lb(x1), x2 = C.lb(x2);
//cout<<area<<endl;
        if(ty == 1){
//cout<<"ADD "<<x1<<endl;
            vert.insert(x1);
            auto it = area.upper_bound(x1); it--;
            int IL = it->first; auto [IR, CID] = it->second;
            if(IL <= x1 && x1 <= IR){
                area.erase(it);
                if(IL < x1) area[IL] = {side(x1,1), CID};
                if(x1 < IR) area[side(x1,0)] = {IR, CID};
            }
            area[x1] = {x1, idx};
        }
        else if(ty == 2){
            if(!contains(x1, x2)) continue;
            auto it = area.upper_bound(x1); it--;
            if(it->second.first < x1) it++;
            int IL = it->first; auto [IR, CID] = it->second;
            if(IL <= x1 && x2 <= IR){
//if(contains(x1, x2)) cout<<idx<<' '<<CID<<endl;
                if(contains(x1, x2)) DS.un(idx, CID);
                continue;
            }
            vector<int> to_erase;
            for(; it->first <= x2; it++){
                to_erase.push_back(it->first);
                IR = it->second.first;
//cout<<idx<<' '<<(it->second.second)<<endl;
                DS.un(idx, it->second.second);
            }
            for(int x: to_erase) area.erase(x);
            area[to_erase[0]] = {IR, idx};
        }
        else if(ty == 3){
//cout<<"REM "<<x1<<endl;
            auto it = area.upper_bound(x1); it--;
            if(it->first == it->second.first) area.erase(it);
            else if(it->first == x1){
                area[side(x1,0)] = it->second;
                area.erase(x1);
            }
            else if(it->second.first == x1)
                it->second = {side(x1,1), it->second.second};
            vert.erase(x1);
        }
    }
    for(int i=0; i<sz(DS.par); i++) COMP+= DS.fd(i) == i;

//cout<<V<<' '<<E<<' '<<COMP<<endl;
    cout << E-V+COMP;
}

Compilation message (stderr)

2014_ho_t5.cpp: In function 'int main()':
2014_ho_t5.cpp:77:27: warning: unused variable 'y' [-Wunused-variable]
     for(auto [y,ty,x1,x2,_]: ev){
                           ^
2014_ho_t5.cpp:77:27: warning: unused variable '_' [-Wunused-variable]
2014_ho_t5.cpp:92:29: warning: unused variable 'y' [-Wunused-variable]
     for(auto [y,ty,x1,x2,idx]: ev){
                             ^

• Subtask 1: 5 / 5
• Subtask 2: 5 / 5
• Subtask 3: 20 / 20
• Subtask 4: 20 / 20
• Subtask 5: 50 / 50