Submission #1320580

#	Time	Username	Problem	Language	Result	Execution time	Memory
1320580		MunkhErdene	Obstacles for a Llama (IOI25_obstacles)	C++17	10 / 100	203 ms	52836 KiB

obstacles

#include <bits/stdc++.h>
#include "obstacles.h"
using namespace std;
#define ll long long
#define pb push_back
#define ff first
#define ss second
#define _ << " " <<
#define yes cout<<"YES\n"
#define no cout<<"NO\n"
#define ull unsigned long long
#define lll __int128
#define all(x) x.begin(),x.end()
#define rall(x) x.rbegin(),x.rend()
#define BlueCrowner ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define FOR(i, a, b) for (ll i = (a); i < (b); i++)
#define FORD(i, a, b) for (ll i = (a); i >= (b); i--)
const ll mod = 1e9 + 7;
const ll mod1 = 998244353;
const ll naim = 1e9;
const ll max_bit = 60;
const ull tom = ULLONG_MAX;
const ll MAXN = 2e6 + 5;
const ll LOG = 20;
const ll NAIM = 1e18;
const ll N = 2e6 + 5;
// ---------- GCD ----------
ll gcd(ll a, ll b) {
    while (b) {
        a %= b;
        swap(a, b);
    }
    return a;
}
// ---------- LCM ----------
ll lcm(ll a, ll b) {
    return a / gcd(a, b) * b;
}
// ---------- Modular Exponentiation ----------
ll modpow(ll a, ll b, ll m = mod) {
    ll c = 1;
    a %= m;
    while (b > 0) {
        if (b & 1) c = c * a % m;
        a = a * a % m;
        b >>= 1;
    }
    return c;
}
// ---------- Modular Inverse (Fermat’s Little Theorem) ----------
ll modinv(ll a, ll m = mod) {
    return modpow(a, m - 2, m);
}
// ---------- Factorials and Inverse Factorials ----------
ll fact[N], invfact[N];
void pre_fact(ll n = N-1, ll m = mod) {
    fact[0] = 1;
    for (ll i = 1; i <= n; i++) fact[i] = fact[i-1] * i % m;
    invfact[n] = modinv(fact[n], m);
    for (ll i = n; i > 0; i--) invfact[i-1] = invfact[i] * i % m;
}
// ---------- nCr ----------
ll nCr(ll n, ll r, ll m = mod) {
    if (r < 0 || r > n) return 0;
    return fact[n] * invfact[r] % m * invfact[n-r] % m;
}
// ---------- Sieve of Eratosthenes ----------
vector<ll> primes;
bool is_prime[N];
void sieve(ll n = N-1) {
    fill(is_prime, is_prime + n + 1, true);
    is_prime[0] = is_prime[1] = false;
    for (ll i = 2; i * i <= n; i++) {
        if (is_prime[i]) {
            for (ll j = i * i; j <= n; j += i)
                is_prime[j] = false;
        }
    }
    for (ll i = 2; i <= n; i++)
        if (is_prime[i]) primes.pb(i);
}
vector<int> t, h;

struct UnionFind {
    vector<int> par, sz, valid, removed;
    UnionFind(int n) {
        par.resize(n);
        sz.resize(n, 1);
        iota(all(par), 0);
        valid.resize(n, 0);
        removed.resize(n, 0);
    }
    void make_valid(int a) {
        a = find(a);
        valid[a] = 1;
    }
    bool is_valid(int a) {
        a = find(a);
        return valid[a];
    }
    void remove(int a) {
        a = find(a);
        removed[a] = 1;
    }
    void restore(int a) {
        a = find(a);
        removed[a] = 0;
    }
    bool is_removed(int a) {
        a = find(a);
        return removed[a];
    }
    int find(int a) {
        if(par[a] == a) return a;
        return par[a] = find(par[a]);
    }
    int unite(int a, int b) {
        a = find(a);
        b = find(b);
        if(a == b) return 0;
        if(valid[a] == 0 && valid[b]) swap(a, b); 
        else if(removed[a] == 1 && removed[b] == 0) {
            swap(a, b);
            restore(b);
        }
        else if(sz[a] < sz[b]) swap(a, b);
        par[b] = a;
        sz[a] += sz[b];
        return 1;
    }
};
UnionFind dsu(MAXN);
void initialize(vector<int> T, vector<int> H) {
    t = T;
    h = H;
    ll n = t.size(), m = h.size();
    multiset<pair<ll,ll>> inactive_columns; 
    multiset<pair<ll,ll>> comps; 
    vector<int> mn(m, 0);
    FOR(i, 0, m) {
        mn[i] = h[i];
        if(h[i] >= t[0]) inactive_columns.insert({h[i], i});
        else {
            comps.insert({mn[i], i});
            dsu.make_valid(i);
        }
        if(i) {
            if(t[0] > h[i] && t[0] > h[i - 1]) {
                ll a = dsu.find(i), b = dsu.find(i - 1);
                if(dsu.is_valid(a)) comps.erase({mn[a], a});
                if(dsu.is_valid(b)) comps.erase({mn[b], b});
                dsu.unite(i, i - 1);
                ll c = dsu.find(i);
                ll d = (c == a ? b : a);
                mn[c] = min(mn[c], mn[d]);
                comps.insert({mn[c], c});
            }
        }
    }
    FOR(i, 1, n) {
        while(!comps.empty()) {
            auto it = prev(comps.end());
            auto px = *it;
            ll k = px.ff;
            ll x = px.ss;
            if(k >= t[i]) {
                comps.erase(it);
                dsu.remove(x);
            } 
            else break;
        }
        while(!inactive_columns.empty()) {
            auto it = inactive_columns.begin();
            auto px = *it;
            ll k = px.ff;
            ll x = px.ss;
            if(dsu.is_valid(x)) {
                inactive_columns.erase(it);
                continue;
            }
            if(t[i] > k) {
                inactive_columns.erase(it);
                if(x < m - 1 && dsu.is_valid(x + 1) && !dsu.is_removed(x + 1)) {
                    ll a = dsu.find(x + 1), b = dsu.find(x);
                    if(dsu.is_valid(a) && !dsu.is_removed(a)) comps.erase({mn[a], a});
                    if(dsu.is_valid(b) && !dsu.is_removed(b)) comps.erase({mn[b], b});
                    dsu.unite(a, b);
                    ll c = dsu.find(a);
                    ll d = (c == a ? b : a);
                    mn[c] = min(mn[c], mn[d]);
                    comps.insert({mn[c], c});
                    ll cur = x;
                    while(cur > 0 && (dsu.is_valid(cur - 1) == 0 || dsu.is_removed(cur - 1)) && h[cur - 1] < t[i]) {
                        ll a2 = cur - 1, b2 = dsu.find(cur);
                        if(dsu.is_valid(b2) && !dsu.is_removed(b2)) comps.erase({mn[b2], b2});
                        if(dsu.is_valid(a2) && !dsu.is_removed(a2)) comps.erase({mn[a2], a2});
                        dsu.unite(a2, b2);
                        ll c2 = dsu.find(a2);
                        ll d2 = (c2 == a2 ? b2 : a2);
                        mn[c2] = min(mn[c2], mn[d2]);
                        comps.insert({mn[c2], c2});
                        cur--;
                    }
                }
                if(x > 0 && dsu.is_valid(x - 1) && dsu.is_removed(x - 1) == 0) {
                    ll a = dsu.find(x - 1), b = dsu.find(x);
                    if(dsu.is_valid(a) && !dsu.is_removed(a)) comps.erase({mn[a], a});
                    if(dsu.is_valid(b) && !dsu.is_removed(b)) comps.erase({mn[b], b});
                    dsu.unite(a, b);
                    ll c = dsu.find(a);
                    ll d = (c == a ? b : a);
                    mn[c] = min(mn[c], mn[d]);
                    comps.insert({mn[c], c});
                    ll cur = x;
                    while(cur < m - 1 && (dsu.is_valid(cur + 1) == 0 || dsu.is_removed(cur + 1)) && h[cur + 1] < t[i]) {
                        ll a2 = cur + 1, b2 = dsu.find(cur);
                        if(dsu.is_valid(b2) && !dsu.is_removed(b2)) comps.erase({mn[b2], b2});
                        if(dsu.is_valid(a2) && !dsu.is_removed(a2)) comps.erase({mn[a2], a2});
                        dsu.unite(a2, b2);
                        ll c2 = dsu.find(a2);
                        ll d2 = (c2 == a2 ? b2 : a2);
                        mn[c2] = min(mn[c2], mn[d2]);
                        comps.insert({mn[c2], c2});
                        cur++;
                    }
                }
            }
            else break;
        }

    }

}
bool can_reach(int l, int r, int s, int d) {
    if(dsu.find(s) == dsu.find(d)) return 1;
    return 0;
}

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