Submission #1274862

#	Time	Username	Problem	Language	Result	Execution time	Memory
1274862		icebear	Joker (BOI20_joker)	C++20	100 / 100	518 ms	12024 KiB

Joker

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

typedef long long ll;
typedef pair<int, int> ii;
typedef pair<int, ii> iii;

template<class T>
    bool minimize(T &a, const T &b) {
        if (a > b) return a = b, true;
        return false;
    }

template<class T>
    bool maximize(T &a, const T &b) {
        if (a < b) return a = b, true;
        return false;
    }

#define FOR(i,a,b) for(int i=(a); i<=(b); ++i)
#define FORR(i,a,b) for(int i=(a); i>=(b); --i)
#define REP(i, n) for(int i=0; i<(n); ++i)
#define RED(i, n) for(int i=(n)-1; i>=0; --i)
#define MASK(i) (1LL << (i))
#define BIT(S, i) (((S) >> (i)) & 1)
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define task "gen"

const int MOD = 1e9 + 7;
const int inf = 1e9 + 27092008;
const ll INF = 1e18 + 27092008;
const int N = 2e5 + 5;
int numNode, numEdge, numQuery, ans[N];
ii edge[N];

struct DisjointSet {
    vector<int> lab;
    bool biparite;
    vector<array<int, 4>> history;
    DisjointSet(int n = 0): lab(n + 5, -1), biparite(true) {}

    int root(int v) {
        return (lab[v] < 0 ? v : root(lab[v]));
    }

    bool unite(int u, int v) {
        u = root(u);
        v = root(v);
        if (u == v) return false;
        if (lab[u] > lab[v]) swap(u, v);
        history.push_back({u, lab[u], v, lab[v]});
        lab[u] += lab[v];
        lab[v] = u;
        return true;
    }

    void add_edge(int u, int v) {
        unite(u, v + numNode);
        unite(v, u + numNode);
        if (root(u) == root(u + numNode)) biparite = false;
        if (root(v) == root(v + numNode)) biparite = false;
    }

    void roll_back(ii snapshot) {
        while((int)history.size() > snapshot.fi) {
            auto H = history.back(); history.pop_back();
            lab[H[0]] = H[1];
            lab[H[2]] = H[3];
        }
        biparite = snapshot.se;
    }

    ii snap() {
        return mp((int)history.size(), biparite);
    }
} dsu;

void DnC(int queryL, int queryR, int ansL, int ansR) {
    if (queryL > queryR) return;
    int queryM = (queryL + queryR) >> 1, ansM = ansL;
    ii snapshot = dsu.snap();

    FOR(i, queryL, queryM - 1) dsu.add_edge(edge[i].fi, edge[i].se);
    if (dsu.biparite == false) {
        FOR(i, queryM, queryR) ans[i] = numEdge + 1;
        dsu.roll_back(snapshot);
        DnC(queryL, queryM - 1, ansL, ansR);
        return;
    }

    FORR(i, ansR, max(queryM, ansL)) {
        dsu.add_edge(edge[i].fi, edge[i].se);
        if (dsu.biparite == false) {
            ansM = i;
            break;
        }
    }

    ans[queryM] = ansM;

    dsu.roll_back(snapshot);
    FOR(i, queryL, queryM) dsu.add_edge(edge[i].fi, edge[i].se);
    DnC(queryM + 1, queryR, ansM, ansR);

    dsu.roll_back(snapshot);
    FORR(i, ansR, ansM + 1) dsu.add_edge(edge[i].fi, edge[i].se);
    DnC(queryL, queryM - 1, ansL, ansM);
}

void init(void) {
    cin >> numNode >> numEdge >> numQuery;
    FOR(i, 1, numEdge) cin >> edge[i].fi >> edge[i].se;
}

void process(void) {
    dsu = DisjointSet(2 * numNode);
    DnC(1, numEdge, 1, numEdge);
    while(numQuery--) {
        int l, r;
        cin >> l >> r;
        cout << (ans[l] > r ? "YES\n" : "NO\n");
        cerr << (ans[l] > r ? "YES\n" : "NO\n");
    }
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    if (fopen(task".inp", "r")) {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    int tc = 1;
//    cin >> tc;
    while(tc--) {
        init();
        process();
    }
    return 0;
}

Compilation message (stderr)

Joker.cpp: In function 'int main()':
Joker.cpp:135:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  135 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Joker.cpp:136:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  136 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 8 / 8
• Subtask 2: 25 / 25
• Subtask 3: 10 / 10
• Subtask 4: 22 / 22
• Subtask 5: 29 / 29
• Subtask 6: 6 / 6