Submission #1076842

#	Time	Username	Problem	Language	Result	Execution time	Memory
1076842		steveonalex	Mergers (JOI19_mergers)	C++17	100 / 100	781 ms	151540 KiB

mergers

// #include "aliens.h"
#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
 
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
#define block_of_code if(true)
 
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(a, b);}
ll lcm(ll a, ll b){return a / gcd(a, b) * b;}
 
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
 
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
double rngesus_d(double l, double r){
    double cur = rngesus(0, MASK(60) - 1);
    cur /= MASK(60) - 1;
    return l + cur * (r - l);
}
 
template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b) {a = b; return true;}
        return false;
    }
 
template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b) {a = b; return true;}
        return false;
    }
 
template <class T>
    void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
        for(auto item: container) out << item << separator;
        out << finish;
    }
 
template <class T>
    void remove_dup(vector<T> &a){
        sort(ALL(a));
        a.resize(unique(ALL(a)) - a.begin());
    }
 
const int N = 5e5 + 69, LOG_N = 19;
 
int root = 1;
int n, k;
int color[N], h[N], parent[N][LOG_N];
vector<int> graph[N];
vector<int> basket[N];
int dp[N], cnt[N];
 
void dfs(int u, int p){
    h[u] = h[p] + 1;
    for(int j = 1; MASK(j) < h[u]; ++j) 
        parent[u][j] = parent[parent[u][j-1]][j-1];
 
    for(int v: graph[u]) if (v != p){
        parent[v][0] = u;
        dfs(v, u);
    }
}
 
int LCA(int u, int v){
    if (h[u] < h[v]) swap(u, v);
    int diff = h[u] - h[v];
    for(int j = 0; j < LOG_N; ++j) if (GETBIT(diff, j)) u = parent[u][j];
    if (u == v) return u;
    for(int j = LOG_N - 1; j>=0; --j) if (parent[u][j] != parent[v][j]){
        u = parent[u][j];
        v = parent[v][j];
    }
    return parent[u][0];
}
 
vector<int> leaf;
void go(int u, int p){
    for(int v: graph[u]) if (v != p){
        go(v, u);
        minimize(dp[u], dp[v]);
    }
    if (u != root && dp[u] == h[u]) {
        leaf.push_back(u);
        cnt[u] = 1;
    }
}

void get_leaf(int u, int p){
    int sum = 0;
    for(int v: graph[u]) if (v != p){
        get_leaf(v, u);
        sum += cnt[v];
    } 
    maximize(cnt[u], sum);
}
 
int main(void){
    ios::sync_with_stdio(0);cin.tie(0); cout.tie(0);
    clock_t start = clock();
 
    cin >> n >> k;
    for(int i = 1; i<n; ++i){
        int u, v; cin >> u >> v;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }
 
    for(int i = 1; i<=n; ++i){
        cin >> color[i];
        basket[color[i]].push_back(i);
    }

    if (n == 1){
        cout << 0 << "\n";
        return 0;
    }
    else if (n == 2){
        cout << (color[1] != color[2]) << "\n";
        return 0;
    }

    for(int i = 1; i<=n; ++i) if (graph[i].size() > 1){
        root = i;
        break;
    }
 
    dfs(root, 0);
 
    for(int i = 1; i<=k; ++i) if (basket[i].size()){
        int lck = basket[i][0];
        for(int j: basket[i]) lck = LCA(lck, j);
        for(int j: basket[i]) dp[j] = h[lck];
    }
 
    go(root, 0);

    sort(ALL(leaf), [&h](int x, int y){return h[x] < h[y];});
    if (leaf.empty()) cout << 0 << "\n";
    else{
        cnt[leaf.back()] = 0;
        get_leaf(leaf.back(),0);

        int ans = cnt[leaf.back()] + 1;
        cout << (ans + 1) / 2 << "\n";
    }
 
    cerr << "Time elapsed: " << clock() - start << " ms\n";
    return 0;
}

Compilation message (stderr)

mergers.cpp: In function 'int main()':
mergers.cpp:149:23: warning: capture of variable 'h' with non-automatic storage duration
  149 |     sort(ALL(leaf), [&h](int x, int y){return h[x] < h[y];});
      |                       ^
mergers.cpp:60:15: note: 'int h [500069]' declared here
   60 | int color[N], h[N], parent[N][LOG_N];
      |               ^

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