Submission #29396

#	Time	Username	Problem	Language	Result	Execution time	Memory
29396		dereotu	Race (IOI11_race)	C++14	100 / 100	2226 ms	44512 KiB

race

#include "race.h"
#include <bits/stdc++.h>
#define pii pair<int,int>
#define mp make_pair
#define pb push_back
#define st first
#define nd second
#define forr(i,A,B) for(int i=A;i<B;++i)
#define space ' '
#define endl '\n'
#define LL long long
using namespace std;

vector <pair<int,int> > adj[200005];

int ans=1e9;
int used[200005],sub[200005];
int k;

int calc_sub(int x,int y){//ok
	sub[x]=1;
	forr(i,0,adj[x].size()){
		if(adj[x][i].nd!=y and !used[adj[x][i].nd]){
			sub[x]+=calc_sub(adj[x][i].nd,x);
		}
	}
	return sub[x];
}

int find_centroid(int x,int y,int treesize){//ok
	forr(i,0,adj[x].size()){
		int u=adj[x][i].nd;
		if(!used[u] and u!=y and sub[u]>treesize/2){
			return find_centroid(u,x,treesize);
		}
	}
	return x;
}

void dfs(int x,int y,int length,int path,map<int,int> &temp_map){
	if(length>k) return;
	if(temp_map.find(length)==temp_map.end()){
		temp_map[length]=path;
	}
	else{
		temp_map[length]=min(temp_map[length],path);
	}
	forr(i,0,adj[x].size()){
		int u=adj[x][i].nd;
		if(u!=y and !used[u]){
			dfs(u,x,length+adj[x][i].st,path+1,temp_map);
		}
	}
}

void merge(map<int,int> &a,map<int,int> &b){
	for(auto it=b.begin();it!=b.end();++it){
		if(a.find(k-it->st)!=a.end()){
			ans=min(ans,a[k-it->st]+it->nd);
		}
	}
	for(auto it=b.begin();it!=b.end();++it){
		if(a.find(it->st)==a.end()){
			a[it->st]=it->nd;
		}
		else a[it->st]=min(a[it->st],it->nd);
	}
}

void calc(int x){//ok
	map<int,int> main_map;
	main_map[0]=0;
	forr(i,0,adj[x].size()){
		int u=adj[x][i].nd;
		if(!used[u]){
			map<int,int> sub_map;
			dfs(u,x,adj[x][i].st,1,sub_map);
			merge(main_map,sub_map);
		}
	}
}

void solve(int x){
	calc_sub(x,-1);
	int centroid=find_centroid(x,-1,sub[x]);
	used[centroid]=1;
	calc(centroid);
	forr(i,0,adj[centroid].size()){
		int u=adj[centroid][i].nd;
		if(!used[u]){
			solve(u);
		}
	}
}


int best_path(int N, int K, int H[][2], int L[])
{
	for(int i=0;i<N;i++){
		adj[H[i][0]].pb(mp(L[i],H[i][1]));
		adj[H[i][1]].pb(mp(L[i],H[i][0]));
	}
	k=K;
	solve(0);
	if(ans==1e9) return -1;
	else return ans;
}

Compilation message (stderr)

race.cpp: In function 'int calc_sub(int, int)':
race.cpp:8:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define forr(i,A,B) for(int i=A;i<B;++i)
race.cpp:22:7:
  forr(i,0,adj[x].size()){
       ~~~~~~~~~~~~~~~~~           
race.cpp:22:2: note: in expansion of macro 'forr'
  forr(i,0,adj[x].size()){
  ^~~~
race.cpp: In function 'int find_centroid(int, int, int)':
race.cpp:8:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define forr(i,A,B) for(int i=A;i<B;++i)
race.cpp:31:7:
  forr(i,0,adj[x].size()){
       ~~~~~~~~~~~~~~~~~           
race.cpp:31:2: note: in expansion of macro 'forr'
  forr(i,0,adj[x].size()){
  ^~~~
race.cpp: In function 'void dfs(int, int, int, int, std::map<int, int>&)':
race.cpp:8:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define forr(i,A,B) for(int i=A;i<B;++i)
race.cpp:48:7:
  forr(i,0,adj[x].size()){
       ~~~~~~~~~~~~~~~~~           
race.cpp:48:2: note: in expansion of macro 'forr'
  forr(i,0,adj[x].size()){
  ^~~~
race.cpp: In function 'void calc(int)':
race.cpp:8:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define forr(i,A,B) for(int i=A;i<B;++i)
race.cpp:73:7:
  forr(i,0,adj[x].size()){
       ~~~~~~~~~~~~~~~~~           
race.cpp:73:2: note: in expansion of macro 'forr'
  forr(i,0,adj[x].size()){
  ^~~~
race.cpp: In function 'void solve(int)':
race.cpp:8:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
 #define forr(i,A,B) for(int i=A;i<B;++i)
race.cpp:88:7:
  forr(i,0,adj[centroid].size()){
       ~~~~~~~~~~~~~~~~~~~~~~~~    
race.cpp:88:2: note: in expansion of macro 'forr'
  forr(i,0,adj[centroid].size()){
  ^~~~

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 22 / 22
• Subtask 4: 57 / 57