Submission #803015

#	Time	Username	Problem	Language	Result	Execution time	Memory
803015		I_Love_EliskaM_	Stations (IOI20_stations)	C++14	100 / 100	810 ms	1048 KiB

stations

#include "stations.h"
#include <bits/stdc++.h>
using namespace std;
#define forn(i,n) for(int i=0;i<n;++i)
#define pb push_back
#define all(x) x.begin(), x.end()
using ll = long long;

const int N=1e3;
int l[N], r[N];
vector<int> adj[N];
int nxt=0;
int col[N];
void dfs(int u, int p, int c) {
	col[u]=c;
	l[u]=nxt++;
	for(auto&v:adj[u]) {
		if (v==p) continue;
		dfs(v,u,!c);
	}
	r[u]=nxt++;
}

vector<int> label(int n, int k, vector<int>u, vector<int> v) {
	forn(i,n) adj[i].clear(); nxt=0;
	forn(i,n-1) {
		adj[u[i]].pb(v[i]);
		adj[v[i]].pb(u[i]);
	}

	dfs(0,-1,0);
	vector<int> ans(n);
	forn(i,n) {
		if (col[i]) {
			ans[i]=l[i];
		} else {
			ans[i]=r[i];
		}
	}
	set<int> s; forn(i,n) s.insert(ans[i]);
	int mex=0;
	map<int,int> c;
	for(auto&x:s) c[x]=mex++;
	forn(i,n) ans[i]=c[ans[i]];
	return ans;
}

int is_ancestor(int l, int r, int y) {
	//x is anc of y
	return l <= y && y <= r;
}

int find_next_station(int s, int t, vector<int> adj) {
	//cout<<"? "<<s<<' '<<t<<": "; for(auto&x:adj) cout<<x<<' '; cout<<'\n';
	if (adj.size()==1) return adj[0];
	if (s > adj.back()) {
		int l=2*adj[1]-1;
		int r=2*s;
		if (is_ancestor(l,r,2*t)) {
			for (int i=1; i<adj.size()-1; ++i) {
				int l=2*adj[i], r=2*adj[i+1]-1;
				if (is_ancestor(l,r,2*t)) return adj[i];
			}
			return adj.back();
		} else {
			return adj[0];
		}
	} else {
		int l=2*s;
		int r=2*adj[adj.size()-2]+1;
		if (is_ancestor(l,r,2*t)) {
			for (int i=1; i<adj.size()-1; ++i) {
				int l=2*adj[i-1]+1, r=2*adj[i];
				if (is_ancestor(l,r,2*t)) return adj[i];
			}
			return adj[0];
		} else {
			return adj.back();
		}
	}
}

Compilation message (stderr)

stations.cpp: In function 'std::vector<int> label(int, int, std::vector<int>, std::vector<int>)':
stations.cpp:4:19: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
    4 | #define forn(i,n) for(int i=0;i<n;++i)
      |                   ^~~
stations.cpp:25:2: note: in expansion of macro 'forn'
   25 |  forn(i,n) adj[i].clear(); nxt=0;
      |  ^~~~
stations.cpp:25:28: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
   25 |  forn(i,n) adj[i].clear(); nxt=0;
      |                            ^~~
stations.cpp: In function 'int find_next_station(int, int, std::vector<int>)':
stations.cpp:60:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   60 |    for (int i=1; i<adj.size()-1; ++i) {
      |                  ~^~~~~~~~~~~~~
stations.cpp:72:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   72 |    for (int i=1; i<adj.size()-1; ++i) {
      |                  ~^~~~~~~~~~~~~

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