Submission #962886

#	Time	Username	Problem	Language	Result	Execution time	Memory
962886		biximo	Stations (IOI20_stations)	C++17	13 / 100	663 ms	1012 KiB

stations

#include "stations.h"
#include <bits/stdc++.h>
using namespace std;
#define N 1005
vector<int> adj[N];
int n, ids[N], sz[N], id;
void dfs(int c, int pr) {
	ids[c] = id++;
	sz[c] = 1;
	for(int i: adj[c]) {
		if(i == pr) continue;
		dfs(i, c);
		sz[c] += sz[i];
	}
}
vector<int> euler_tree() {
	id = 0;
	dfs(0, -1);
	vector<int> ans(n);
	for(int i = 0; i < n; i ++) {
		sz[i] --;
		ans[i] = ids[i]*1000+sz[i];
		assert(ids[i]< 1000);
		assert(sz[i]<1000);
	}
	return ans;
}
vector<int> nddds;
void DFS(int c, int pr) {
	nddds.push_back(c);
	for(int i: adj[c]) {
		if(i == pr) continue;
		DFS(i, c);
	}
}
vector<int> flatten() {
	nddds.clear();
	for(int i = 0; i < n; i ++) {
		if(adj[i].size() == 1) {
			DFS(i, -1);
			vector<int> nds = nddds;
			vector<int> ans(n);
			for(int j = 0; j < n; j ++) {
				ans[nds[j]] = j;
			}
			return ans;
		}
	}
	return vector<int>();
	assert(0);
}
std::vector<int> label(int ngb, int k, std::vector<int> u, std::vector<int> v) {
	n = ngb;
	for(auto&i: adj) i.clear();
	for(int i = 0; i < n-1; i ++) {
		adj[u[i]].push_back(v[i]);
		adj[v[i]].push_back(u[i]);
	}
	int ms = 0;
	for(auto&i: adj) ms = max(ms, (int)i.size());
	if(k >= 1000000) {
		return euler_tree();
	} 
	for(int i = 0; i < n-1; i ++) {
		if(u[i] == i+1 && v[i] == i/2 || u[i] == i/2 && v[i] == i+1) continue;
		return flatten();
	}
	vector<int> nds;
	for(int i = 0; i < n; i ++) nds.push_back(i);
	return nds;
}
struct Nd {
	int id, sz;
	Nd(int i) : id(i/1000), sz(i%1000) {
	}
};
int findEuler(int s, int t, vector<int> c) {
	int sid = s/1000, ssz = s%1000;
	int tid = t/1000, tsz = t%1000;
	int cnt = 0;
	for(int i: c) {
		int nsz = i%1000;
		if(nsz >= ssz) {
			++cnt;
		}
	}
	assert(cnt <= 1);
	if(sid <= tid && tid <= sid + ssz) {
		for(int i: c) {
			int nid = i/1000, nsz = i%1000;
			if(nid <= tid && tid <= nid + nsz) {
				return i;
			}
		}	
		assert(0);
	}
	for(int i: c) {
		int nsz = i%1000;
		if(nsz >= ssz) {
			return i;
		}
	}
	assert(0);
}
int findFlat(int s, int t, vector<int> c) {
	if(s < t) {
		if(c.size() == 1) return c[0];
		return c[1];
	} else {
		return c[0];
	}
}
int ds[N], pr[N];
int findWeird(int s, int t, vector<int> c) {
	for(auto&i: adj) i.clear();
	for(int i = 0; i < max(s,t); i ++) {
		adj[i+1].push_back(i/2);
		adj[i/2].push_back(i+1);
	}
	for(auto&i: ds) i = N;
	queue<int> que;
	que.push(t); ds[t] = 0; pr[t] = 0;
	while(que.size()) {
		int c = que.front(); que.pop();
		for(int i: adj[c]) {
			if(ds[i] > ds[c]+1) {
				ds[i] = ds[c]+1;
				pr[i] = c;
				que.push(i);
			}
		}
	}
	return pr[s];
}
int find_next_station(int s, int t, std::vector<int> c) {
	int mv = max(s, t);
	for(int i: c) mv = max(mv, i);
	if(mv >= 1000) {
		return findEuler(s,t,c);
	}
	if(c.size() == 1 && (c[0] == s+1 || c[0] == s-1)) {
		return findFlat(s,t,c);
	}
	if(c.size() == 2 && c[0] == s-1 && c[1] == s+1) {
		return findFlat(s,t,c);
	}
	return findWeird(s,t,c);
}
// int main() {
// 	int nv, nk;
// 	cin >> nv >> nv >> nk;
// 	vector<int> u, v;
// 	vector<int> ptss[N];
// 	for(int i = 1; i < nv; i ++) {
// 		int a, b;
// 		cin >> a >> b;
// 		u.push_back(a);
// 		v.push_back(b);
// 		ptss[a].push_back(b);
// 		ptss[b].push_back(a);
// 	}
// 	vector<int> lb = label(nv, nk, u, v);;
// 	for(int i: lb) cout << i << " ";
// 	// int q;
// 	// cin >> q;
// 	// while(q--) {
// 	// 	int a, b, c;
// 	// 	cin >> a >> b >> c;
// 	// 	vector<int> adjs;
// 	// 	for(int i: ptss[a]) {
// 	// 		adjs.push_back(lb[i]);
// 	// 	}
// 	// 	cout << find_next_station(lb[a], lb[b], adjs) << " ";
// 	// }
// }

Compilation message (stderr)

stations.cpp: In function 'std::vector<int> label(int, int, std::vector<int>, std::vector<int>)':
stations.cpp:65:18: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   65 |   if(u[i] == i+1 && v[i] == i/2 || u[i] == i/2 && v[i] == i+1) continue;
stations.cpp: In function 'int findEuler(int, int, std::vector<int>)':
stations.cpp:79:20: warning: unused variable 'tsz' [-Wunused-variable]
   79 |  int tid = t/1000, tsz = t%1000;
      |                    ^~~

• Subtask 1: 5 / 5
• Subtask 2: 8 / 8
• Subtask 3: 0 / 16
• Subtask 4: 0 / 10
• Subtask 5: 0 / 61