Submission #1145598

#	Time	Username	Problem	Language	Result	Execution time	Memory
1145598		monkey133	Team Coding (EGOI24_teamcoding)	C++20	0 / 100	4094 ms	45840 KiB

Main

#include <bits/stdc++.h>
using namespace std;
 
typedef int ll;
typedef pair<int,int> pi;
 
const int MAXN = 100005;
 
int n, k, label = 0;
int blk = 316;
int color[MAXN], par[MAXN], in[MAXN], out[MAXN], cnt[MAXN], dep[MAXN];
int big[MAXN];
vector<int> adj[MAXN], nodelist[MAXN];
vector<int> deplist[MAXN]; // for each color, record all depths (later sorted & uniqued)
 
// We'll store frequency maps as sorted vectors of (key, count) pairs.
vector<pi> dp[MAXN], dp2[MAXN], dp3[MAXN], dp4[MAXN], dp5[MAXN];
// For each color (0<=c<k) store the global frequency of nodes of that color by depth.
vector<vector<pi>> colMapVec;  // size = k, indexed by color
 
// The final answer is stored as (res, -swaps) so that max() gives lex–order.
pi ans = { -1000000000, -1000000000 };
 
// ----- Helper routines for “dp” vectors (sorted by key) -----
 
// Binary search for key in sorted vector "vec"; returns count if found, else 0.
inline int getValue(const vector<pi>& vec, int key) {
    int lo = 0, hi = (int)vec.size()-1;
    while(lo <= hi) {
        int mid = (lo+hi)/2;
        if(vec[mid].first == key)
            return vec[mid].second;
        else if(vec[mid].first < key)
            lo = mid+1;
        else
            hi = mid-1;
    }
    return 0;
}
 
// Insert or update key in sorted vector "vec" by adding "val".
inline void addValue(vector<pi>& vec, int key, int val) {
    auto it = std::lower_bound(vec.begin(), vec.end(), make_pair(key,0));
    if(it != vec.end() && it->first == key)
        it->second += val;
    else
        vec.insert(it, {key, val});
}
 
// Merge two sorted vectors (dest and src) summing counts for equal keys.
inline void mergeSortedVectors(vector<pi>& dest, const vector<pi>& src) {
    vector<pi> merged;
    merged.reserve(dest.size() + src.size());
    int i = 0, j = 0;
    while(i < dest.size() && j < src.size()){
        if(dest[i].first == src[j].first){
            merged.push_back({dest[i].first, dest[i].second + src[j].second});
            i++; j++;
        }
        else if(dest[i].first < src[j].first){
            merged.push_back(dest[i]);
            i++;
        }
        else {
            merged.push_back(src[j]);
            j++;
        }
    }
    while(i < dest.size()){
        merged.push_back(dest[i]);
        i++;
    }
    while(j < src.size()){
        merged.push_back(src[j]);
        j++;
    }
    dest = move(merged);
}
 
// ----- DFS 1: Euler Tour + depth computation; record each node’s depth in deplist[color] -----
void precomp1(int x = 0) {
    in[x] = ++label;
    for (int u: adj[x]) {
        dep[u] = dep[x] + 1;
        precomp1(u);
    }
    out[x] = label;
    deplist[color[x]].push_back(dep[x]);
}
 
// ----- DFS 2: DSU on tree for "dp" arrays; also build dp2 for later use for small colors ----- 
void precomp2(int x = 0) {
    // Update global frequency for this node’s color.
    addValue(colMapVec[color[x]], dep[x], 1);
    for (int u: adj[x]) {
        precomp2(u);
        // Merge dp[u] into dp[x] (small-to–large merging)
        if(dp[x].size() < dp[u].size())
            swap(dp[x], dp[u]);
        mergeSortedVectors(dp[x], dp[u]);
        dp[u].clear();
    }
    addValue(dp[x], dep[x], 1);
    // Build dp2[x] for nodes whose color is “small”
    if (!big[color[x]]) {
        for (int d: deplist[color[x]]) {
            int val = getValue(dp[x], d);
            if(val)
                addValue(dp2[x], d, val);
        }
    }
}
 
// ----- DFS for “big” colors: merge dp4 and dp5 arrays -----
void dfs(int x, int c, int yes = 1) {
    for (int u: adj[x]) {
        dfs(u, c, yes & (color[x] != c));
        if(dp4[x].size() < dp4[u].size())
            swap(dp4[x], dp4[u]);
        mergeSortedVectors(dp4[x], dp4[u]);
        if(dp5[x].size() < dp5[u].size())
            swap(dp5[x], dp5[u]);
        mergeSortedVectors(dp5[x], dp5[u]);
        dp4[u].clear(); dp5[u].clear();
    }
    if(yes && color[x] == c) {
        int res = 0, res2 = 0;
        // For every depth (from the unique depths for color c) that is deeper than dep[x]
        for (int d: deplist[c]) {
            if(d <= dep[x])
                continue;
            int a = getValue(dp4[x], d);
            int b = getValue(colMapVec[c], d);
            int take = min(a, b);
            res += take;
            int cval = getValue(dp5[x], d);
            res2 += max(0, take - cval);
        }
        ans = max(ans, make_pair(res, -res2));
    }
    addValue(dp4[x], dep[x], 1);
    if(c == color[x])
        addValue(dp5[x], dep[x], 1);
}
 
// ----- Process “small” colors (those with cnt <= blk) -----
void solve(int c) {
    int sz = nodelist[c].size();
    // For every pair of nodes of color c where one is an ancestor of the other,
    // update dp3 for the ancestor.
    for (int i = 0; i < sz; i++){
        int x = nodelist[c][i];
        for (int j = i+1; j < sz; j++){
            int y = nodelist[c][j];
            if(in[x] > in[y])
                swap(x,y);
            if(in[x] <= in[y] && in[y] <= out[x])
                addValue(dp3[x], dep[y], 1);
        }
    }
    // Then for each node of color c, use its dp2 and dp3 to compute candidate answer.
    for (int i = 0; i < sz; i++){
        int x = nodelist[c][i];
        int res = 0, res2 = 0;
        for (int d: deplist[c]){
            if(d <= dep[x])
                continue;
            int a = getValue(dp2[x], d);
            int b = getValue(colMapVec[c], d);
            int take = min(a, b);
            res += take;
            int cval = getValue(dp3[x], d);
            res2 += max(0, take - cval);
        }
        dp2[x].clear(); dp3[x].clear();
        ans = max(ans, make_pair(res, -res2));
    }
}
 
// ----- Main -----
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    
    cin >> n >> k;
    // Initialize colMapVec so that colMapVec[c] will hold frequency (by depth) for color c.
    colMapVec.resize(k);
    
    for (int i = 0; i < n; i++){
        cin >> color[i];
        cnt[color[i]]++;
        nodelist[color[i]].push_back(i);
    }
    for (int i = 0; i < k; i++){
        if(cnt[i] > blk)
            big[i] = 1;
    }
    for (int i = 1; i < n; i++){
        cin >> par[i];
        adj[par[i]].push_back(i);
    }
    
    precomp1();
    // For each color, sort and unique the list of depths (to drive our loops later)
    for (int 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();
    
    // Process each color: use DFS for big colors and a different method for small colors.
    for (int i = 0; i < k; i++){
        if(big[i]){
            for (int 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: 0 / 12
• Subtask 2: 0 / 19
• Subtask 3: 0 / 27
• Subtask 4: 0 / 23
• Subtask 5: 0 / 19