Submission #770866

#	Time	Username	Problem	Language	Result	Execution time	Memory
770866		marvinthang	Fountain Parks (IOI21_parks)	C++17	100 / 100	359 ms	42600 KiB

parks

/*************************************
*    author: marvinthang             *
*    created: 02.07.2023 11:47:17    *
*************************************/

#include "parks.h"
#include <bits/stdc++.h>

using namespace std;

#define                  fi  first
#define                  se  second
#define                left  ___left
#define               right  ___right
#define                TIME  (1.0 * clock() / CLOCKS_PER_SEC)
#define             MASK(i)  (1LL << (i))
#define           BIT(x, i)  ((x) >> (i) & 1)
#define  __builtin_popcount  __builtin_popcountll
#define              ALL(v)  (v).begin(), (v).end()
#define           REP(i, n)  for (int i = 0, _n = (n); i < _n; ++i)
#define          REPD(i, n)  for (int i = (n); i--; )
#define        FOR(i, a, b)  for (int i = (a), _b = (b); i < _b; ++i) 
#define       FORD(i, b, a)  for (int i = (b), _a = (a); --i >= _a; ) 
#define       FORE(i, a, b)  for (int i = (a), _b = (b); i <= _b; ++i) 
#define      FORDE(i, b, a)  for (int i = (b), _a = (a); i >= _a; --i) 
#define        scan_op(...)  istream & operator >> (istream &in, __VA_ARGS__ &u)
#define       print_op(...)  ostream & operator << (ostream &out, const __VA_ARGS__ &u)
#ifdef LOCAL
    #include "debug.h"
#else
    #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
    #define DB(...) 23
    #define db(...) 23
    #define debug(...) 23
#endif

template <class U, class V> scan_op(pair <U, V>)  { return in >> u.first >> u.second; }
template <class T> scan_op(vector <T>)  { for (size_t i = 0; i < u.size(); ++i) in >> u[i]; return in; }
template <class U, class V> print_op(pair <U, V>)  { return out << '(' << u.first << ", " << u.second << ')'; }
template <size_t i, class T> ostream & print_tuple_utils(ostream &out, const T &tup) { if constexpr(i == tuple_size<T>::value) return out << ")";  else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup); }
template <class ...U> print_op(tuple<U...>) { return print_tuple_utils<0, tuple<U...>>(out, u); }
template <class Con, class = decltype(begin(declval<Con>()))> typename enable_if <!is_same<Con, string>::value, ostream&>::type operator << (ostream &out, const Con &con) { out << '{'; for (__typeof(con.begin()) it = con.begin(); it != con.end(); ++it) out << (it == con.begin() ? "" : ", ") << *it; return out << '}'; }

// end of template

struct DisjointSet {
    
    int n, *lab = nullptr;

    DisjointSet(int _n = 0) {
        resize(_n);
    }

    void reset(void) {
        memset(lab, -1, (n + 1) * sizeof(int));
    }

    void resize(int _n) {
         if (lab != nullptr) delete[] lab;
         n = _n;
         lab = new int[n + 1];
         reset();
    }

    int find(int u) {
        assert(u <= n);
        return lab[u] < 0 ? u : lab[u] = find(lab[u]);
    }

    bool connected(int u, int v) { return find(u) == find(v); }
    bool isRoot(int u) { return lab[u] < 0; }
    int size(int u) { return -lab[find(u)]; }

    bool join(int u, int v) {
        if ((u = find(u)) == (v = find(v))) return false;
        if (lab[u] > lab[v]) swap(u, v);
        lab[u] += lab[v];
        lab[v] = u;
        return true;
    }

};

using DSU = DisjointSet;

int construct_roads(vector <int> x, vector <int> y) {
    int n = x.size();
    map <pair <int, int>, int> id;
    vector <pair <int, int>> p;
    REP(i, n) {
        p.emplace_back(x[i], y[i]);
        id[p.back()] = i;
    }
    sort(ALL(p));
    vector <int> U, V, A, B;
    set <pair <int, int>> used;
    DSU dsu(n);
    auto addEdge = [&] (int u, int v, int a, int b) {
        if (!~u || !~v || !used.insert(make_pair(a, b)).se || !dsu.join(u, v)) return false;
        U.push_back(u);
        V.push_back(v);
        A.push_back(a);
        B.push_back(b);
        return true;
    };
    for (auto [x, y]: p) {
        int a = id[make_pair(x, y)];
        int b = id.count(make_pair(x - 2, y)) ? id[make_pair(x - 2, y)] : -1;
        int c = id.count(make_pair(x, y - 2)) ? id[make_pair(x, y - 2)] : -1;
        if (x + y & 3) {
            addEdge(a, b, x - 1, y - 1);
            addEdge(a, c, x + 1, y - 1);
        } else {
            addEdge(a, c, x - 1, y - 1);
            addEdge(a, b, x - 1, y + 1);
        }
    }
    if (U.size() != n - 1) return 0;
    build(U, V, A, B);
    return 1;
}

Compilation message (stderr)

parks.cpp: In function 'int construct_roads(std::vector<int>, std::vector<int>)':
parks.cpp:110:15: warning: suggest parentheses around '+' in operand of '&' [-Wparentheses]
  110 |         if (x + y & 3) {
      |             ~~^~~
parks.cpp:118:18: warning: comparison of integer expressions of different signedness: 'std::vector<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
  118 |     if (U.size() != n - 1) return 0;
      |         ~~~~~~~~~^~~~~~~~

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 15 / 15
• Subtask 4: 20 / 20
• Subtask 5: 20 / 20
• Subtask 6: 30 / 30