Submission #602329

#	Time	Username	Problem	Language	Result	Execution time	Memory
602329		OttoTheDino	Joker (BOI20_joker)	C++17	100 / 100	703 ms	26604 KiB

Joker

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

#define rep(i,s,e)                          for (int i = s; i <= e; ++i)
#define rrep(i,s,e)                         for (int i = s; i >= e; --i)
#define fi                                  first
#define se                                  second
#define pb                                  push_back
#define len(a)                              (int)a.size()
typedef vector<int> vi;
typedef pair<int,int> ii;

const int mx = 2e5;
vi adj[mx+1];

int par[mx+1], h[mx+1], tp[mx+1], dp[mx+1], cnt, m;
ii e[mx+1];
vector<vi> history;

ii get_par (int u) {
    if (u==par[u]) return {u, tp[u]};
    ii res = get_par (par[u]); 
    ii ans = {res.fi, res.se^tp[u]};
    return {ans};
}

bool merge (int u, int v) {
    ii paru = get_par(u), parv = get_par(v);
    if (paru.fi==parv.fi) {
        history.pb({parv.fi, parv.fi, paru.se==parv.se, 0});
        return paru.se==parv.se;
    }
    if (h[paru.fi]<h[parv.fi]) swap(paru, parv);
    history.pb({parv.fi, paru.fi, h[paru.fi]==h[parv.fi], parv.se==paru.se});
    h[paru.fi] += h[paru.fi]==h[parv.fi];
    par[parv.fi] = paru.fi; 
    tp[parv.fi] ^= parv.se==paru.se;
    return 0;
}

int rollback (int t) {
    int sum = 0;
    while (t--) {
        int a = history.back()[0], b = history.back()[1], c = history.back()[2], d = history.back()[3];
        history.pop_back();
        if (a==b) {
            sum += c;
            continue;
        }
        par[a] = a;
        h[b] -= c;
        tp[a] ^= d;
    }
    return sum;
}

void go (int l1, int l2, int r1, int r2) {
    if (r1==r2) {
        rep (i,l1,l2) dp[i] = r1;
        return;
    }

    int lm = (l1+l2)/2, rm = r2, steps = 0;
    rep (i,l1,lm) {
        if (i) {
            cnt += merge(e[i].fi, e[i].se);
            steps++;
        }
    }

    bool suc = 0;

    if (cnt) {
        suc = 1;
        goto nxt;
    }

    while (true) {
        if (rm<=m) {
            cnt += merge(e[rm].fi, e[rm].se);
            steps++;
        }
        if (cnt) {
            suc = 1;
            break;
        }
        if (rm==lm+1) break;
        --rm;
    }

    nxt:

    cnt -= rollback(steps);

    if (!suc) {
        //don't need to do anything with dp[l1]...dp[lm]
        if (l2>=lm+1) {
            steps = 0;
            rep (i,l1,lm) {
                if (i) {
                    cnt += merge(e[i].fi, e[i].se);
                    steps++;
                }
            }
            go(lm+1, l2, lm+2, r2); 
            cnt -= rollback(lm-l1);
        }
        return;
    }

    dp[lm] = rm;

    if (lm-1>=l1) {
        steps = 0;
        rep (i,rm+1,r2) {
            if (i<=m) {
                cnt += merge(e[i].fi, e[i].se); 
                steps++;
            }
        }
        go (l1, lm-1, r1, rm);
        cnt -= rollback(steps);
    }

    if (l2>=lm+1) {
        steps = 0;
        rep (i,l1,lm) {
            if (i) {
                cnt += merge(e[i].fi, e[i].se);
                steps++;
            }
        }
        go (lm+1,l2,max(lm+2,r1),r2);
        cnt -= rollback(steps);
    }
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);

    int n, q; cin >>n >> m >> q;

    rep (i,1,n) {
        par[i] = i;
        h[i] = 1;
    }

    rep (i,1,m) cin >> e[i].fi >> e[i].se;


    go (0,m,1,m+1);

    while (q--) {
        int l, r; cin >> l >> r;
        cout << (r<dp[l-1]?"YES":"NO") << "\n";
    }

    return 0;
}

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