Submission #201241

#	Time	Username	Problem	Language	Result	Execution time	Memory
201241		model_code	Matching (COCI20_matching)	C++17	110 / 110	1191 ms	170496 KiB

matching

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

#define TRACE(x) cerr << #x << " = " << x << endl
#define _ << " _ " <<

#define fi first
#define se second

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef vector<int> vi;

const int INF = 1e9;

const int OFF = 1 << 17;
struct SegTree {
    set<int> t[2 * OFF];

    SegTree() {
        for (int i = 1; i < 2 * OFF; i++)
            t[i].insert(INF);
    }

    void insert(int l, int r, int x, int i = 1, int lo = 0, int hi = OFF) {
        if (r <= lo || hi <= l) return;
        if (l <= lo && hi <= r) t[i].insert(x);
        else {
            int mid = (lo + hi) / 2;
            insert(l, r, x, 2 * i + 0, lo, mid);
            insert(l, r, x, 2 * i + 1, mid, hi);
        }
    }

    void erase(int l, int r, int x, int i = 1, int lo = 0, int hi = OFF) {
        if (r <= lo || hi <= l) return;
        if (l <= lo && hi <= r) t[i].erase(x);
        else {
            int mid = (lo + hi) / 2;
            erase(l, r, x, 2 * i + 0, lo, mid);
            erase(l, r, x, 2 * i + 1, mid, hi);
        }
    }

    int lower_bound(int i, int x) {
        int lb = INF;
        for (i += OFF; i > 0; i /= 2)
            lb = min(lb, *t[i].lower_bound(x));
        return lb;
    }
} M[2], P[2];


const int MAXN = 1e5 + 10;
int x[MAXN][2];
vector<int> V[MAXN][2];
bool vis[MAXN];
int cycle_id[MAXN];
vector<vector<int>> cycle;
queue<pii> Q[2];

void no() {
    cout << "NE\n";
    exit(0);
}

void find_path(int i, bool is_cycle) {
    if (vis[i]) return;

    if (is_cycle) cycle.push_back(vector<int>());

    int st_o = V[x[i][0]][0].size() != 2, o = st_o;
    while (!vis[i]) {
        vis[i] = true;
        if (V[x[i][o]][o].size() == 1) break;
        assert(V[x[i][o]][o].size() == 2);

        int j = V[x[i][o]][o][0] ^ V[x[i][o]][o][1] ^ i;
        assert(x[i][o] == x[j][o]);

        if (is_cycle) {
            cycle.back().push_back(i);
            cycle_id[i] = (int)cycle.size() - 1;

            int l = x[i][o ^ 1], r = x[j][o ^ 1];
            if (l > r) swap(l, r);
            P[o].insert(l, r + 1, x[i][o]);
        } else {
            if (o == st_o)
                Q[o].push({i, j});
        }

        i = j;
        o ^= 1;
    }

    if (is_cycle) cycle.back().push_back(i);
    if (!is_cycle && o == st_o) no();
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> x[i][0] >> x[i][1];
        V[x[i][0]][0].push_back(i);
        V[x[i][1]][1].push_back(i);
    }

    for (int i = 0; i < MAXN; i++)
        for (int j : {0, 1})
            assert(V[i][j].size() <= 2);

    for (int i = 0; i < MAXN; i++)
        for (int j : {0, 1})
            if (V[i][j].size() == 1)
                find_path(V[i][j][0], false);
    for (int i = 0; i < MAXN; i++)
        for (int j : {0, 1})
            if (V[i][j].size() == 2)
                find_path(V[i][j][0], true);

    vector<bool> matched_cycle(cycle.size(), false);
    
    vector<pii> sol;
    while (!(Q[0].empty() && Q[1].empty())) {
        int o = Q[0].empty();
        int i = Q[o].front().fi, j = Q[o].front().se;
        Q[o].pop();

        assert(x[i][o] == x[j][o]);

        int l = x[i][o ^ 1], r = x[j][o ^ 1];
        if (l > r) swap(l, r);

        if (M[o ^ 1].lower_bound(x[i][o], l) <= r) no();

        for (int y = P[o ^ 1].lower_bound(x[i][o], l); y <= r;
                y = P[o ^ 1].lower_bound(x[i][o], l)) {
            int c = cycle_id[V[y][o ^ 1][0]];
            if (matched_cycle[c]) continue;
            matched_cycle[c] = true;
            for (int k = 0; k < (int)cycle[c].size() - 1; k++) {
                int oc = k & 1, ic = cycle[c][k], jc = cycle[c][k + 1];
                int lc = x[ic][oc ^ 1], rc = x[jc][oc ^ 1];
                if (lc > rc) swap(lc, rc);
                P[oc].erase(lc, rc + 1, x[ic][oc]);
                if (oc == o) Q[oc].push({ic, jc});
            }
        }

        M[o].insert(l, r, x[i][o]);
        sol.push_back({i, j});
    }

    for (int i = 0; i < (int)cycle.size(); i++)
        if (!matched_cycle[i])
            for (int j = 0; j < (int)cycle[i].size() - 1; j += 2)
                sol.push_back({cycle[i][j], cycle[i][j + 1]});

    cout << "DA\n";
    for (auto p : sol) cout << p.fi + 1 << " " << p.se + 1 << "\n";

    return 0;
}

• Subtask 1: 5 / 5
• Subtask 2: 6 / 6
• Subtask 3: 7 / 7
• Subtask 4: 40 / 40
• Subtask 5: 52 / 52