제출 #1145591

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1145591		monkey133	Team Coding (EGOI24_teamcoding)	C++20	62 / 100	4120 ms	964648 KiB

Main

#include <bits/stdc++.h>
using namespace std;
 
// A custom hash to reduce collisions and the overhead of unordered_map.
struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        x += 0x9e3779b97f4a7c15ULL;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9ULL;
        x = (x ^ (x >> 27)) * 0x94d049bb133111ebULL;
        return x ^ (x >> 31);
    }
    size_t operator()(uint64_t x) const {
        static const uint64_t random_constant = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + random_constant);
    }
};
 
//––– Typedefs and macros –––
typedef int ll;
typedef pair<ll, ll> pi;
 
#define pb push_back
#define mp make_pair
 
ll const blk = 1000;
 
ll n, k, label = 0;
ll color[100005], par[100005], in[100005], out[100005], cnt[100005], dep[100005], big[100005];
vector<ll> adj[100005], nodelist[100005];
 
// Instead of an unordered_set for each color’s depths, we use a vector.
vector<ll> deplist[100005];
 
// We now define our maps with the custom hash.
unordered_map<ll, ll, custom_hash> 
    dp[100005], 
    dp2[100005], 
    dp3[100005], 
    dp4[100005], 
    dp5[100005],
    colMap[100005]; // this stores, per color, the overall counts by depth
 
// Answer stored as (res, -swaps) so that max() works lex–order.
pi ans = mp(-1000000000, -1000000000);
 
//––– precomp1: Euler Tour + collect depths for each color –––
void precomp1(ll x = 0) {
    in[x] = ++label;
    for (ll u : adj[x]) {
        dep[u] = dep[x] + 1;
        precomp1(u);
    }
    out[x] = label;
    // Instead of deplist[color[x]].insert(...), we simply push_back.
    deplist[color[x]].pb(dep[x]);
}
 
//––– precomp2: Build dp and record “col” frequencies –––
void precomp2(ll x = 0) {
    // Instead of a separate “col” map, we store counts in colMap indexed by color.
    colMap[color[x]][dep[x]]++;
    for (ll u : adj[x]) {
        precomp2(u);
        // Small-to–large merging: always merge the smaller map into the larger.
        if (dp[x].size() < dp[u].size()) swap(dp[x], dp[u]);
        for (auto &p : dp[u])
            dp[x][p.first] += p.second;
        dp[u].clear();
    }
    dp[x][dep[x]]++;
    // Only build dp2 if this color is “small” (here we check by big[color])
    if (!big[color[x]]) {
        for (ll d : deplist[color[x]])
            dp2[x][d] += dp[x][d];
    }
}
 
//––– dfs: process “big” colors –––
void dfs(ll x, ll c, ll yes = 1) {
    for (ll u : adj[x]) {
        dfs(u, c, yes & (color[x] != c));
        if (dp4[x].size() < dp4[u].size()) swap(dp4[u], dp4[x]);
        for (auto &p : dp4[u])
            dp4[x][p.first] += p.second;
        if (dp5[x].size() < dp5[u].size()) swap(dp5[u], dp5[x]);
        for (auto &p : dp5[u])
            dp5[x][p.first] += p.second;
        dp4[u].clear();
        dp5[u].clear();
    }
    if (yes && color[x] == c) {
        ll res = 0, res2 = 0;
        // Iterate only over unique depths for this color.
        for (ll d : deplist[c]) {
            if (d <= dep[x]) continue;
            ll take = min(dp4[x][d], colMap[c][d]);
            res += take;
            res2 += max(0, take - dp5[x][d]);
        }
        ans = max(ans, mp(res, -res2));
    }
    dp4[x][dep[x]]++;
    if (c == color[x])
        dp5[x][dep[x]]++;
}
 
//––– solve: process “small” colors –––
void solve(ll c) {
    int sz = nodelist[c].size();
    for (int i = 0; i < sz; i++) {
        for (int j = i + 1; j < sz; j++) {
            ll x = nodelist[c][i], y = nodelist[c][j];
            if (in[x] > in[y]) swap(x, y);
            if (in[x] <= in[y] && in[y] <= out[x])
                dp3[x][dep[y]]++;
        }
    }
    for (int i = 0; i < sz; i++) {
        ll x = nodelist[c][i];
        ll res = 0, res2 = 0;
        for (ll d : deplist[c]) {
            if (d <= dep[x]) continue;
            ll take = min(dp2[x][d], colMap[c][d]);
            res += take;
            res2 += max(0, take - dp3[x][d]);
        }
        dp2[x].clear();
        dp3[x].clear();
        ans = max(ans, mp(res, -res2));
    }
}
 
//––– main –––
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    
    cin >> n >> k;
    for (ll i = 0; i < n; i++){
        cin >> color[i];
        cnt[color[i]]++;
        nodelist[color[i]].pb(i);
    }
    for (ll i = 0; i < k; i++){
        if (cnt[i] > blk)
            big[i] = 1;
    }
    for (ll i = 1; i < n; i++){
        cin >> par[i];
        adj[par[i]].pb(i);
    }
    
    precomp1();
    // For each color, sort and unique the list of depths
    for (ll i = 0; i < k; i++){
        sort(deplist[i].begin(), deplist[i].end());
        deplist[i].erase(unique(deplist[i].begin(), deplist[i].end()), deplist[i].end());
    }
    precomp2();
    
    for (ll i = 0; i < k; i++){
        if (big[i]) {
            // Clear temporary maps before processing a new “big” color.
            for (ll j = 0; j < n; j++){
                dp5[j].clear();
                dp4[j].clear();
            }
            dfs(0, i, 1);
        } else {
            solve(i);
        }
    }
    cout << ans.first + 1 << " " << -ans.second << "\n";
    return 0;
}

• Subtask 1: 12 / 12
• Subtask 2: 0 / 19
• Subtask 3: 27 / 27
• Subtask 4: 23 / 23
• Subtask 5: 0 / 19