Submission #203382

#	Time	Username	Problem	Language	Result	Execution time	Memory
203382		theStaticMind	Mergers (JOI19_mergers)	C++14	34 / 100	498 ms	262148 KiB

mergers

#include<bits/stdc++.h>
#define pb push_back
#define ii pair<int,int>
#define all(x) (x).begin(),(x).end()
#define INF 100000000000000000
#define modulo 1000000007
#define mod 998244353
#define int long long int
using namespace std;

struct Tree{
      vector<vector<int> >& adj;
      vector<vector<int> > anc;
      vector<vector<int> > cost;
      vector<int> depth;
      vector<int> sub;
      vector<bool> vis;
      int n;
      int root;

      Tree(vector<vector<int> >& a, int N = 1e6, int r = 1): adj(a){
            n = N + 5;
            root = r;
            anc = vector<vector<int> > (25, vector<int>(n, 0));
            depth = vector<int>(n, 0);
            vis = vector<bool> (n, false);
            sub = vector<int> (n, 1);

            init(root, -1);

            for(int d = 1; d < 25; d++){

                  for(int x = 0; x < n; x++){

                        anc[d][x] = anc[d - 1][anc[d - 1][x]];

                  }

            }

      }

      void init(int x, int pre){

            for(int i = 0; i < adj[x].size(); i++){

                int y = adj[x][i];

                  if(y == pre)continue;

                  anc[0][y] = x;

                  depth[y] = depth[x] + 1;

                  init(y, x);

                  sub[x] += sub[y];

            }

      }

      int LCA(int x, int y){
            if(depth[x] < depth[y])swap(x,y);

            while(depth[x] != depth[y]){

                  int diff = depth[x] - depth[y];

                  diff = log2(diff&-diff);

                  x = anc[diff][x];

            }

            if(x == y) return x;

            for(int i = 24; i >= 0; i--){

                  if(anc[i][x] != anc[i][y]){

                        x = anc[i][x];

                        y = anc[i][y];

                  }

            }

            return anc[0][x];

      }

      int up(int x, int k){

            while(k){

                  int diff = log2(k&-k);

                  k -= k & -k;

                  x = anc[diff][x];

            }

            return x;

      }

      int dist(int x, int y){

            int l = LCA(x, y);

            return depth[x] + depth[y] - 2 * depth[l];

      }

};

vector<vector<int> > adj(500005);
vector<int> val(500005);
vector<int> comp[500005];
vector<int> up(500005);
vector<int> sub(500005);
unordered_map<int,int> edge;
vector<bool> virt(500005, false);

int num(int x, int y){
      return edge[x * 1e6 + y];
}


void dfs(int x, int pre, vector<int>& depth){

      for(auto y : adj[x]){
            if(y == pre) continue;
            dfs(y, x, depth);
            if(depth[up[x]] > depth[up[y]])
            up[x] = up[y];
      }
      if(pre != 0 && up[x] != x){
            virt[num(x, pre)] = true;
      }
}

void get(int x, int pre, int& ans, int root){
      sub[x] = 0;
      if(pre != 0 && virt[num(x, pre)] == false) sub[x] = 1;
      for(auto y : adj[x]){
            if(y == pre)continue;
            get(y, x, ans, root);
            sub[x] += sub[y];
      }
      if(pre != 0 && pre != root && virt[num(x, pre)] == false && sub[x] == 1) ans++;
}

int32_t main(){
      ios_base::sync_with_stdio(false);
      cin.tie(NULL);
      int n, k;
      cin >> n >> k;
      if(n == 1){
            cout << 0;
            return 0;
      }
      for(int i = 0; i < n - 1; i++) {
            int x, y;
            cin >> x >> y;
            adj[x].pb(y);
            adj[y].pb(x);
            edge[x * 1e6 + y] = i;
            edge[y * 1e6 + x] = i;
      }
      for(int i = 1; i <= n; i++){
            cin >> val[i];
            comp[val[i]].pb(i);
            up[i] = i;
      }

      Tree A(adj);

      for(int i = 0; i < 500005; i++){
            if(comp[i].empty()) continue;
            int l = comp[i][0];
            for(auto x : comp[i]){
                  l = A.LCA(x, l);
            }
            for(auto x : comp[i]){
                  up[x] = l;
            }
      }

      dfs(1, 0, A.depth);
      int root = 0;
      for(auto itr = edge.begin(); itr != edge.end(); itr++) {
            int x = itr->first / 1e6;
            int y = itr->first % 1000000;
            int w = itr->second;
            if(virt[w]) continue;
            if(A.depth[x] < A.depth[y]) swap(x, y);
            if((root == 0 || A.depth[x] > A.depth[root])) root = x;
      }
      int ans = 0;
      get(root, 0, ans, root);
      if(root) ans++;
      cout << (ans + 1) / 2;

}

Compilation message (stderr)

mergers.cpp: In member function 'void Tree::init(long long int, long long int)':
mergers.cpp:45:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int i = 0; i < adj[x].size(); i++){
                            ~~^~~~~~~~~~~~~~~

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