Submission #521073

#	Time	Username	Problem	Language	Result	Execution time	Memory
521073		cig32	Mergers (JOI19_mergers)	C++17	70 / 100	1308 ms	262148 KiB

mergers

#include "bits/stdc++.h"
using namespace std;
const int MAXN = 5e5 + 10;
vector<int> adj[MAXN];
int fin[MAXN];
int s[MAXN];
int dsu[MAXN];
int set_of(int u) {
  if(dsu[u] == u) return u;
  return dsu[u] = set_of(dsu[u]);
}
void union_(int u, int v) {
  dsu[set_of(u)] = set_of(v);
}
vector<int> e;
int dep[MAXN];
int tin[MAXN];
int tim = 0;
void dfs1(int node, int prev, int cur) {
  e.push_back(node);
  dep[node] = cur;
  tin[node] = ++tim;
  for(int x: adj[node]) {
    if(x != prev) {
      dfs1(x, node, cur + 1);
      e.push_back(node);
    }
  }
}
pair<int, int> st[20][2*MAXN];
int l[MAXN], r[MAXN];
int lca(int x, int y) {
  int m1 = min(l[x], l[y]);
  int m2 = max(r[x], r[y]);
  int k = 32 - __builtin_clz(m2 - m1 + 1) - 1;
  return min(st[k][m1], st[k][m2 - (1<<k) + 1]).second;
}
int delta[MAXN];
bool cmp(int a, int b) {
  return tin[a] < tin[b];
}
map<pair<int, int>, bool> lit;
int dfs2(int node, int prev) {
  int s = delta[node];
  for(int x: adj[node]) {
    if(x != prev) s += dfs2(x, node);
  }
  if(s == 0) lit[{node, prev}] = lit[{prev, node}] = 1;
  return s;
}
int32_t main() {
  int n,k;cin >> n >> k;
  for(int i=1;i<n;i++) {
    int a,b;cin >> a >> b;
    adj[a].push_back(b);
    adj[b].push_back(a);
  }
  for(int i=1; i<=n; i++) cin >> s[i];
  for(int i=0; i<=n; i++) dsu[i] = i;
  dfs1(1, -1, 0);
  for(int i=0; i<e.size(); i++) r[e[i]] = i;
  for(int i=e.size()-1; i>=0; i--) l[e[i]] = i;
  for(int i=0; i<e.size(); i++) st[0][i] = {dep[e[i]], e[i]};
  for(int i=1; i<20; i++) {
    for(int j=0; j<e.size(); j++) {
      if(j + (1<<i) - 1 < e.size()) {
        st[i][j] = min(st[i-1][j], st[i-1][j+(1<<(i-1))]);
      }
    }
  }
  vector<int> wow[k+1];
  for(int i=1; i<=n; i++) {
    wow[s[i]].push_back(i);
  }
  for(int i=1; i<=k; i++) {
    if(wow[i].size() == 1) continue;
    sort(wow[i].begin(), wow[i].end(), cmp);
    int l = lca(wow[i][0], wow[i][1]);
    for(int j=0; j<wow[i].size(); j++) {
      l = lca(l, wow[i][j]);
      delta[wow[i][j]]++;
    }
    delta[l] -= wow[i].size();
  }
  dfs2(1, -1);
  for(int i=1; i<=n; i++) {
    for(int x: adj[i]) {
      if(!lit[{i, x}]) {
        union_(i, x);
      }
    }
  }
  lit.clear();
  for(int i=1; i<=n; i++) {
    for(int x: adj[i]) {
      if(set_of(i) != set_of(x) && lit[{set_of(i), set_of(x)}] == 0) {
        lit[{set_of(i), set_of(x)}] = 1;
        lit[{set_of(x), set_of(i)}] = 1;
        fin[set_of(i)]++;
        fin[set_of(x)]++;
      }
    }
  }
  int s = 0;
  for(int i=1; i<=n; i++) {
    s += (fin[i] == 1);
  }
  cout << (s + 1) / 2 << "\n";
}
 

Compilation message (stderr)

mergers.cpp: In function 'int32_t main()':
mergers.cpp:61:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   61 |   for(int i=0; i<e.size(); i++) r[e[i]] = i;
      |                ~^~~~~~~~~
mergers.cpp:63:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   63 |   for(int i=0; i<e.size(); i++) st[0][i] = {dep[e[i]], e[i]};
      |                ~^~~~~~~~~
mergers.cpp:65:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   65 |     for(int j=0; j<e.size(); j++) {
      |                  ~^~~~~~~~~
mergers.cpp:66:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   66 |       if(j + (1<<i) - 1 < e.size()) {
      |          ~~~~~~~~~~~~~~~^~~~~~~~~~
mergers.cpp:79:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   79 |     for(int j=0; j<wow[i].size(); j++) {
      |                  ~^~~~~~~~~~~~~~

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