Submission #962849

#	Time	Username	Problem	Language	Result	Execution time	Memory
962849		biximo	Stations (IOI20_stations)	C++17	8 / 100	640 ms	1068 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] = 0;
	for(int i: adj[c]) {
		if(i == pr) continue;
		dfs(i, c);
		sz[c] += sz[i] + 1;
	}
}
vector<int> euler_tree() {
	id = 0;
	dfs(0, -1);
	vector<int> ans(n);
	for(int i = 0; i < n; i ++) {
		ans[i] = ids[i]*1000+sz[i];
	}
	return ans;
}
vector<int> flatten() {
	for(int i = 0; i < n; i ++) {
		if(adj[i].size() == 1) {
			vector<int> nds(1,i);
			int pr = i, c = adj[i][0];
			while(adj[c].size() != 1) {
				nds.push_back(c);
				if(pr == adj[c][0]) {
					swap(pr, c);
					c = adj[pr][1];
				} else {
					swap(pr, c);
					c = adj[pr][0];
				}
			}
			nds.push_back(c);
			vector<int> ans(n);
			for(int i = 0; i < n; i ++) {
				ans[nds[i]] = i;
			}
			return nds;
		}
	}
	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) {
	Nd cur = Nd(s), nxt = Nd(t);
	if(nxt.id >= cur.id && nxt.id <= cur.id+cur.sz) {
		for(int i: c) {
			Nd it = Nd(i);
			if(nxt.id >= it.id && nxt.id <= it.id+it.sz) {
				return i;
			}
		}	
		assert(0);
	}
	for(int i: c) {
		Nd it = Nd(i);
		if(it.sz >= cur.sz) {
			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);
}

Compilation message (stderr)

stations.cpp: In function 'std::vector<int> label(int, int, std::vector<int>, std::vector<int>)':
stations.cpp:63:18: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   63 |   if(u[i] == i+1 && v[i] == i/2 || u[i] == i/2 && v[i] == i+1) continue;

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