Submission #920014

#	Time	Username	Problem	Language	Result	Execution time	Memory
920014		thunopro	Race (IOI11_race)	C++14	100 / 100	320 ms	40016 KiB

race

#include<bits/stdc++.h>
using namespace std ; 
#define maxn 200009 
#define ll long long 
#define fi first 
#define se second 
#define pb push_back 
#define left id<<1
#define right id<<1|1 
#define re exit(0); 

const int mod = 1e9+7; 
const int INF = 1e9; 

typedef vector<int> vi; 
typedef pair<int,int> pii;
typedef vector<pii> vii;  
typedef vector<ll> vl;

void add ( int &a , int b ) 
{
	a += b ; 
	if ( a > mod ) a -= mod ; 
	if ( a < 0 ) a += mod ; 
}

template <typename T> void chkmin ( T &a , T b ) { if ( a > b ) a = b ; }
template <typename T> void chkmax ( T &a , T b ) { if ( a < b ) a = b ; }

int _pow ( int a , int n ) 
{
	if ( n == 0 ) return 1 ;
	int res = _pow (a,n/2) ; 
	if ( n % 2 ) return 1ll*res*res%mod*a%mod ; 
	else return 1ll*res*res%mod ; 
}

void rf () 
{
	freopen ("bai1.inp","r",stdin) ;
}

const int maxm = 1e6+9 ; 
int n , k ; 
int h [maxn][2] , l [maxn] ; 
int res = INF ; 
vii adjList [maxn] ; 
int sz [maxn] , cnt [maxm] ; 
bool vis [maxn] ; 

int dfs_sz ( int u , int par ) 
{
	sz [u] = 1 ; 
	for ( auto x : adjList [u] ) 
	{
		int v = x.fi ; 
		if ( v == par || vis [v] ) continue ;
		sz [u] += dfs_sz (v,u) ; 		 
	}
	return sz [u] ; 
}

int find_centroid ( int u , int par , int n ) 
{
	for ( auto x : adjList [u] ) 
	{
		int v = x.fi ; 
		if ( v == par || vis [v] ) continue ; 
		if ( sz [v]*2 > n ) return find_centroid (v,u,n) ; 
	}
	return u ; 
}

void dfs1 ( int u , int par , int dep , int len ) 
{
	if ( len > k ) return ; 
	chkmin (res,dep+cnt[k-len]) ; 
	for ( auto x : adjList [u] ) 
	{
		int v = x.fi , w = x.se ; 
		if ( v == par || vis [v] ) continue ; 
		dfs1 (v,u,dep+1,len+w) ; 
	}
}

void dfs2 ( int u , int par , int dep , int len ) 
{
	if ( len > k ) return ;
	chkmin (cnt[len],dep) ; 
	for ( auto x : adjList [u] ) 
	{
		int v = x.fi , w = x.se ; 
		if ( v == par || vis [v] ) continue ; 
		dfs2 (v,u,dep+1,len+w) ; 
	}
}

void dfs3 ( int u , int par , int dep , int len ) 
{
	if ( len > k ) return ; 
	cnt [len] = INF ; 
	for ( auto x : adjList [u] ) 
	{
		int v = x.fi , w = x.se ; 
		if ( v == par || vis [v] ) continue ; 
		dfs3 (v,u,dep+1,len+w) ;   
	}
}
void solve ( int u ) 
{
	int n = dfs_sz (u,-1) ;
	u = find_centroid (u,-1,n) ; 
	cnt [0] = 0 ; 
	for ( auto x : adjList [u] ) 
	{
		int v = x.fi , w = x.se ;
		if ( vis [v] ) continue ; 
		dfs1 (v,u,1,w) ;
		dfs2 (v,u,1,w) ; 
	}
	for ( auto x : adjList [u] ) 
	{
		int v = x.fi , w = x.se ; 
		if ( vis [v] ) continue ; 
		dfs3 (v,u,1,w) ; 
	}
	vis [u] = true ; 
	for ( auto x : adjList [u] ) 
	{
		int v = x.fi , w = x.se ; 
		if ( vis [v] ) continue ; 
		solve (v) ; 
	}
}

int best_path ( int N , int K , int H[][2] , int L[] ) 
{
	n = N , k = K ; 
	for ( int i = 0 ; i < n-1 ; i ++ ) for ( int j = 0 ; j < 2 ; j ++ ) h [i][j] = H [i][j] ; 
	for ( int i = 0 ; i < n-1 ; i ++ ) l [i] = L [i] ; 
	for ( int i = 0 ; i < n-1 ; i ++ ) 
	{
		int u = h [i][0] , v = h [i][1] ; 
		adjList [u] . pb ({v,l[i]}) ; 
		adjList [v] . pb ({u,l[i]}) ; 
	}
	
	memset (cnt,0x3f,sizeof cnt) ; 
	solve (0) ; 
	
	if ( res == INF ) res = - 1 ; 
	return res ; 
}
//int main () 
//{
//	ios_base::sync_with_stdio(0); 
//	cin.tie(0);cout.tie(0); 
//	rf () ; 
//	cin >> n >> k ; 
//	for ( int i = 1 ; i < n ; i ++ ) for ( int j = 0 ; j < 2 ; j ++ ) cin >> h [i][j] ; 
//	for ( int i = 1 ; i < n ; i ++ ) cin >> l [i] ; 
//	cout << best_path (n,k,h,l) ; 
//}

Compilation message (stderr)

race.cpp: In function 'void solve(int)':
race.cpp:130:18: warning: unused variable 'w' [-Wunused-variable]
  130 |   int v = x.fi , w = x.se ;
      |                  ^
race.cpp: In function 'void rf()':
race.cpp:40:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |  freopen ("bai1.inp","r",stdin) ;
      |  ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

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