Submission #1027764

#	Time	Username	Problem	Language	Result	Execution time	Memory
1027764		caterpillow	Marriage questions (IZhO14_marriage)	C++17	100 / 100	534 ms	6236 KiB

marriage

    #include <bits/stdc++.h>

    using namespace std;

    using db = long double;
    using ll = long long;
    using pl = pair<ll, ll>;
    using pi = pair<int, int>;
    #define vt vector
    #define f first
    #define s second
    #define pb push_back
    #define all(x) x.begin(), x.end() 
    #define size(x) ((int) (x).size())
    #define FOR(i, a, b) for (int i = (a); i < (b); i++)
    #define ROF(i, a, b) for (int i = (b) - 1; i >= (a); i--)
    #define F0R(i, b) FOR (i, 0, b)
    #define endl '\n'
    const ll INF = 1e18;
    const int inf = 1e9;

    template<typename Tuple, size_t... Is>
    void print_tuple(const Tuple& t, index_sequence<Is...>) {
        ((cerr << (Is == 0 ? "{" : ", ") << get<Is>(t)), ...);
        cerr << "}";
    }

    template<typename... Args>
    ostream& operator<<(ostream& os, const tuple<Args...>& t) {
        print_tuple(t, index_sequence_for<Args...>{});
        return os;
    }

    ostream& operator<<(ostream& os, string& s) {
        for (char c : s) os << c; 
        return os;
    }

    template<template<typename> class Container, typename T>
    ostream& operator<<(ostream& os, Container<T> o) {
        os << "{"; 
        int g = size(o); 
        for (auto i : o) os << i << ((--g) == 0 ? "" : ", "); 
        os << "}";
        return os;
    }

    template<typename T, typename V>
    ostream& operator<<(ostream& os, const pair<T, V> p) {
        os << "{" << p.f << ", " << p.s << "}";
        return os;
    }

    template <typename T, typename... V>
    void printer(const char *names, T &&head, V &&...tail) {
        int i = 0;
        while (names[i] != '\0' && names[i] != ',') i++;
        constexpr bool is_str = is_same_v<decay_t<T>, const char*>;
        if constexpr (is_str) cerr << head; // ignore directly passed strings
        else cerr.write(names, i) << " = " << head; 
        if constexpr (sizeof...(tail)) cerr << (is_str ? "" : ","), printer(names + i + 1, tail...);
        else cerr << endl;
    }

    #ifdef LOCAL
    #define dbg(...) std::cerr << __LINE__ << ": ", printer(#__VA_ARGS__, __VA_ARGS__)
    #else
    #define dbg(x...)
    #define cerr if (0) std::cerr
    #endif

    /*

    range perfect matching goes crazy

    since kuhn's is more efficient when lhs is small, we need the girls to be on the left
    we want to find the maximum r for each l, and two pointer it

    */

    int n, m, k; // n is lhs (girls), m is rhs (boys)
    vt<unordered_set<int>> adj; // l -> r
    vt<int> mate; // mate = rhs -> lhs
    vt<bool> seen;

    bool dfs(int u) {
        if (seen[u]) return false;
        seen[u] = true;
        for (int v : adj[u]) {
            if (mate[v] == -1 || dfs(mate[v])) {
                mate[v] = u;
                return true;
            }
        }
        return false;
    }

    main() {
        cin.tie(0)->sync_with_stdio(0);
        
        cin >> m >> n >> k;
        adj.resize(n);
        mate.resize(m, -1);

        vt<vt<int>> radj(m);
        F0R (i, k) {
            int u, v; cin >> u >> v; u--, v--;
            // u is boy, v is girl
            radj[u].pb(v);
        }

        // enqueue all the unmatched girls
        queue<int> to_match;
        F0R (i, n) to_match.push(i);

        // attempt to augment from u on lhs
        auto augment = [&] (int u) {
            seen.assign(n, 0);
            return dfs(u);
        };

        ll ans = 0;
        int r = -1;

        F0R (l, m) {
            while (size(to_match)) {
                // try augment
                while (size(to_match) && augment(to_match.front())) {
                    to_match.pop();
                }

                if (!size(to_match)) break;
                // still bad

                if (r == m - 1) {
                    cout << ans << endl;
                    return 0;
                }
                r++;

                // add these edges
                for (int u : radj[r]) assert(adj[u].insert(r).s);
            }

            // add # of possible right endpoints for l
            dbg(l, r);
            ans += m - r;
            assert(r - l + 1 >= n);

            // remove edges
            for (int u : radj[l]) assert(adj[u].erase(l));

            // check if we unmatched someone by removing l
            if (mate[l] != -1) {
                to_match.push(mate[l]);
                mate[l] = -1;
            }
        }
        cout << ans << endl;
    }

Compilation message (stderr)

marriage.cpp:98:5: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   98 |     main() {
      |     ^~~~

• Subtask 1: 100 / 100