Submission #1108930

#	Time	Username	Problem	Language	Result	Execution time	Memory
1108930		doducanh	Factories (JOI14_factories)	C++14	100 / 100	3065 ms	240124 KiB

factories

#include <bits/stdc++.h>
using namespace std;
 
#define endl "\n"
#define f(i,a,b) for(int i=int(a);i<int(b);++i)
 
#define pr pair
#define ar array
#define fr first
#define sc second
#define vt vector
#define pb push_back
#define eb emplace_back
#define LB lower_bound  
#define UB upper_bound
#define PQ priority_queue
 
#define SZ(x) ((int)(x).size())
#define all(a) (a).begin(),(a).end()
#define allr(a) (a).rbegin(),(a).rend()
#define mem(a,b) memset(a, b, sizeof(a))
 
 
template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
const long long INF = 1e16;
 
struct edge {
  int node, weight;
  edge(int _node, int _weight) : node(_node), weight(_weight)  {}
};
 
struct centroid_decomposition {
  int N;
  vector<vector<edge>> adj;
  vector<int> depth;
  vector<int> subtree_size;
  // parent of a node in centroid tree.
  vector<int> centroid_parent;
  vector<int> node_list;
  // gives the distance of each node to its descendants in centroid tree.
  vector<vector<long long>> dis; // from node to its ancestors.
 	bool found_centroid;
	
  void init(int _N) {
    N = _N;
    adj.assign(N, {});
    depth.resize(N);
    subtree_size.resize(N);
    centroid_parent.assign(N, -1);
    dis.resize(N,{});
  }
	
	
  void add_edge(int u, int v, int w) {
    assert(u != v);
    adj[u].emplace_back(edge(v,w));
    adj[v].emplace_back(edge(u,w));
  }
  
  // Erasing edges is O(number of nodes remaining) which is fine within our decomposition.
	void erase_edge(int from, int to) {
		for(edge &e : adj[from]) {
      if(e.node == to) {
        swap(e, adj[from].back());
        adj[from].pop_back();
        return;
      }
    }
    assert(false);
  }
 
  int dfs(int node, long long weight = 0, int parent = -1, int root = -1) {
  	if(parent < 0) {
    	root = node;
      node_list.clear();
    }
 
  	if(found_centroid){
  		dis[node].pb(weight);
  	}
  	
    subtree_size[node] = 1;
    node_list.push_back(node);
 
    for(edge &e : adj[node]) {
    	if(e.node != parent) {
      	subtree_size[node] += dfs(e.node, e.weight + weight, node, parent < 0 ? node : root);
      }
    }
 
    return subtree_size[node];
  }
 
  int centroid(int root) {
  	int n = dfs(root);
    bool found;
 
    // Repeatedly move to the subtree that is at least half of the tree, if such a subtree exists.
    do {
      found = false;
 
      for(edge &e : adj[root]){
        if(subtree_size[e.node] < subtree_size[root] && 2 * subtree_size[e.node] >= n) {
          root = e.node;
          found = true;
          break;
      	}
      }
    } while(found);
 
    return root;
  }
 
	// centroid parent of root of centroid tree is -1
  void solve(int root) {
  	found_centroid = false;
  	root = centroid(root);
  	found_centroid = true;
    dfs(root);
 
    for(int node : node_list){
      if(node != root){
         centroid_parent[node] = root;
			}
    }
 
  	for(edge &e : adj[root]){
    	erase_edge(e.node, root);
    }
 
  	// Recurse after solving root, so that edge erasures don't cause incorrect results.
    for(edge &e : adj[root]){
      solve(e.node);
    }
  }
}cd;
 
 
vt<long long> ans;
 
 
void turn_on(int _i){
	for(int i = _i, cnt = 0; ~i; i = cd.centroid_parent[i], ++cnt){
		ckmin(ans[i],cd.dis[_i][cnt]);
	}
}
 
void turn_off(int _i){
	for(int i = _i; ~i; i = cd.centroid_parent[i]){
		ans[i] = INF;
	}
}
 
 
 
 
 
 
 
 
 
 
void Init(int N, int A[], int B[], int D[]) {
	
	ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
	
	cd.init(N);
	ans.assign(N,INF);
	f(e,0,N-1){
		cd.add_edge(A[e],B[e],D[e]);
	}
	cd.solve(0);
	
	f(i,0,N) reverse(all(cd.dis[i]));
 
	return;
}
 
 
long long Query(int S, int X[], int T, int Y[]) {
	
	
	f(i,0,S) turn_on(X[i]);
	
	
	long long res = INF;
	f(i,0,T){
		for(int j = Y[i], cnt = 0; ~j; j = cd.centroid_parent[j], ++cnt){
			ckmin(res, cd.dis[Y[i]][cnt] + ans[j]);
		}
	}
	
	
	
	f(i,0,S) turn_off(X[i]);
	
  return res;
}
 
 
 
 

• Subtask 1: 15 / 15
• Subtask 2: 18 / 18
• Subtask 3: 67 / 67