Submission #142487

#	Time	Username	Problem	Language	Result	Execution time	Memory
142487		popovicirobert	Link (CEOI06_link)	C++14	100 / 100	687 ms	51076 KiB

link

#include <bits/stdc++.h>
#pragma GCC optimize ("Ofast")
#define lsb(x) (x & (-x))
#define ll long long
#define ull unsigned long long
// 217
// 44


/*const int MOD = 998244353;

inline int lgput(int a, int b) {
    int ans = 1;
    while(b > 0) {
        if(b & 1) ans = (1LL * ans * a) % MOD;
        b >>= 1;
        a = (1LL * a * a) % MOD;
    }
    return ans;
}

inline void mod(int &x) {
    if(x >= MOD)
        x -= MOD;
}

inline void add(int &x, int y) {
    x += y;
    mod(x);
}

inline void sub(int &x, int y) {
    x += MOD - y;
    mod(x);
}

inline void mul(int &x, int y) {
    x = (1LL * x * y) % MOD;
}

inline int inv(int x) {
    return lgput(x, MOD - 2);
}*/

/*int fact[], invfact[];

inline void prec(int n) {
    fact[0] = 1;
    for(int i = 1; i <= n; i++) {
        fact[i] = (1LL * fact[i - 1] * i) % MOD;
    }
    invfact[n] = lgput(fact[n], MOD - 2);
    for(int i = n - 1; i >= 0; i--) {
        invfact[i] = (1LL * invfact[i + 1] * (i + 1)) % MOD;
    }
}

inline int comb(int n, int k) {
    if(n < k) return 0;
    return (1LL * fact[n] * (1LL * invfact[k] * invfact[n - k] % MOD)) % MOD;
}*/

using namespace std;

const int INF = 1e9;

int main() {
    //ifstream cin("A.in");
    //ofstream cout("A.out");
    int i, j, n, k;
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);

    cin >> n >> k;
    vector < vector <int> > g(n + 1);
    vector <int> to(n + 1), deg(n + 1);
    for(i = 1; i <= n; i++) {
        int a, b;
        cin >> a >> b;
        to[a] = b, deg[b]++;
        g[b].push_back(a);
    }
    vector <int> dst(n + 1, INF), vis(n + 1);
    queue <int> Q;
    int ans = 0;
    for(i = 1; i <= n; i++) {
        if(deg[i] == 0) {
            Q.push(i);
            dst[i] = 1;
            ans += (i != 1);
        }
    }
    dst[1] = 0;
    while(Q.size()) {
        int nod = Q.front();
        vis[nod] = 1;
        Q.pop();
        for(auto it : g[nod]) {
            dst[nod] = min(dst[nod], dst[it] + 1);
        }
        if(dst[nod] == k + 1) {
            dst[nod] = 1;
            ans++;
        }
        deg[to[nod]]--;
        if(deg[to[nod]] == 0) {
            Q.push(to[nod]);
        }
    }
    //cerr << ans;
    for(i = 1; i <= n; i++) {
        for(auto it : g[i]) {
            dst[i] = min(dst[i], dst[it] + 1);
        }
    }
    for(i = 1; i <= n; i++) {
        if(vis[i]) continue;
        vector <int> cyc;
        for(j = i; vis[j] == 0; j = to[j]) {
            vis[j] = 1;
            cyc.push_back(j);
        }
        priority_queue < pair <int, int> > pq;
        int sz = cyc.size();
        for(j = 0; j < sz; j++) {
            cyc.push_back(cyc[j]);
            pq.push({-dst[cyc[j]], cyc[j]});
        }
        while(pq.size()) {
            auto cur = pq.top();
            pq.pop();
            if(dst[to[cur.second]] > -cur.first + 1) {
                dst[to[cur.second]] = -cur.first + 1;
                pq.push({cur.first - 1, to[cur.second]});
            }
        }
        vector <int> nxt(2 * sz);
        int last = -1;
        for(j = 2 * sz - 1; j >= 0; j--) {
            if(dst[cyc[j]] > k) {
                last = j;
            }
            nxt[j] = last;
        }
        vector < vector <int> > anc(20, vector <int>(2 * sz));
        for(j = 0; j < 2 * sz; j++) {
            anc[0][j] = (j + k < 2 * sz ? nxt[j + k] : -1);
        }
        for(int bit = 1; bit < 20; bit++) {
            for(j = 0; j < 2 * sz; j++) {
                anc[bit][j] = (anc[bit - 1][j] == -1 ? -1 : anc[bit - 1][anc[bit - 1][j]]);
            }
        }
        int mn = INF;
        for(j = 0; j < sz; j++) {
            if(dst[cyc[j]] <= k) continue;
            int cur = 0, p = j;
            for(int bit = 19; bit >= 0; bit--) {
                if(anc[bit][p] != -1 && anc[bit][p] < j + sz) {
                    p = anc[bit][p];
                    cur += (1 << bit);
                }
            }
            mn = min(mn, cur + 1);
        }
        if(mn == INF) mn = 0;
        ans += mn;
    }

    cout << ans;

    return 0;
}

• Subtask 1: 100 / 100