Submission #377943

#	Time	Username	Problem	Language	Result	Execution time	Memory
377943		2qbingxuan	Mergers (JOI19_mergers)	C++14	0 / 100	83 ms	35604 KiB

mergers

#include <bits/stdc++.h>
#ifdef local
#define debug(a...) qqbx(#a, a)
template <typename ...T> void qqbx(const char *s, T ...a) {
    int cnt = sizeof...(T);
    ((std::cerr << "\033[1;32m(" << s << ") = (") , ... , (std::cerr << a << (--cnt ? ", " : "\033[0m)\n")));
}
#define safe std::cerr<<__PRETTY_FUNCTION__<<" line "<<__LINE__<<" safe\n"
#else
#define debug(...) ((void)0)
#define safe ((void)0)
#endif // local
#define all(v) begin(v),end(v)
#define pb emplace_back
#define sort_uni(v) sort(all(v)), v.erase(unique(all(v)), v.end())

using namespace std;
using ll = int64_t;
template <typename T> using min_heap = priority_queue<T, vector<T>, greater<T>>;
const ll INF = 1e18;
const int maxn = 500025, inf = 1e9;

struct Segtree {
    int n;
    vector<int> st;
    function<int(int,int)> Func;
    int Id;
    Segtree(int _n, function<int(int,int)> f, int id) : n(_n), st(_n * 2, id), Func(f), Id(id) {}
    int& operator[](int idx) { return st[idx + n]; }
    void build() {
        for (int i = n-1; i > 0; i--)
            st[i] = Func(st[i<<1], st[i<<1|1]);
    }
    int query(int l, int r) {
        int res = Id;
        for (l += n, r += n; l < r; l >>= 1, r >>= 1) {
            if (l&1) res = Func(res, st[l++]);
            if (r&1) res = Func(res, st[--r]);
        }
        return res;
    }
};

struct Dsu {
    vector<int> pa, rk;
    Dsu(int n) : pa(n), rk(n) { iota(all(pa), 0); }
    int anc(int x) { return x==pa[x] ? x : pa[x] = anc(pa[x]); }
    bool join(int x, int y) {
        if ((x=anc(x)) == (y=anc(y))) return false;
        if (rk[x] < rk[y]) swap(x, y);
        return pa[y] = x, rk[x] != rk[y] || ++rk[x];
    }
};

vector<int> g[maxn], adj[maxn];
int color[maxn];
int pa[maxn], in[maxn], ou[maxn], tot;
int mn[maxn], mx[maxn];
void dfs(int i, int p) {
    pa[i] = p;
    in[i] = tot++;
    for (int j: g[i]) {
        if (j == p) continue;
        dfs(j, i);
    }
    ou[i] = tot;
}

signed main() {
    ios_base::sync_with_stdio(0), cin.tie(0);
    int n, k;
    cin >> n >> k;
    for (int i = 1; i < n; i++) {
        int a, b;
        cin >> a >> b;
        g[a].emplace_back(b);
        g[b].emplace_back(a);
    }
    for (int i = 1; i <= n; i++) cin >> color[i];
    dfs(1, 0);
    for (int i = 1; i <= k; i++) mn[i] = inf, mx[i] = -inf;
    for (int i = 1; i <= n; i++) {
        int c = color[i];
        mn[c] = min(mn[c], in[i]);
        mx[c] = max(mx[c], in[i]);
    }
    // qx <= x <= y <= qy
    // x <= qx <= qy <= y
    Segtree R(n, [](int a, int b){ return max(a, b); }, 0);
    Segtree L(n, [](int a, int b){ return min(a, b); }, inf);
    Dsu dsu(n + 1);
    for (int i = 1; i <= k; i++) {
        debug(mn[i], mx[i]);
        R[mn[i]] = max(R[mn[i]], mx[i]);
        L[mx[i]] = min(L[mx[i]], mn[i]);
    }
    R.build();
    L.build();
    for (int i = 1; i <= n; i++) {
        if (R.query(in[i], ou[i]) >= ou[i] || L.query(in[i], ou[i]) < in[i]) {
            debug(i, pa[i]);
            dsu.join(i, pa[i]);
        }
    }
    vector<int> deg(n + 1);
    for (int i = 1; i <= n; i++) {
        for (int j: g[i]) {
            int a = dsu.anc(i);
            int b = dsu.anc(j);
            if (a != b)
                adj[a].push_back(b);
        }
    }
    for (int i = 1; i <= n; i++) sort_uni(adj[i]);
    int leaf = 0;
    for (int i = 1; i <= n; i++) {
        int deg = adj[i].size();
        debug(deg);
        if (deg == 1) ++leaf;
    }
    debug(leaf);
    cout << (leaf + 1) / 2 << '\n';
}

• Subtask 1: 0 / 10
• Subtask 2: 0 / 24
• Subtask 3: 0 / 14
• Subtask 4: 0 / 22
• Subtask 5: 0 / 30