Submission #896186

#	Time	Username	Problem	Language	Result	Execution time	Memory
896186		thunopro	Bridges (APIO19_bridges)	C++14	100 / 100	1844 ms	142236 KiB

bridges

#include<bits/stdc++.h>
using namespace std ; 
#define ll long long 
#define maxn 200009 
#define fi first 
#define se second 
#define pb push_back 
#define left id<<1 
#define right id<<1|1 
#define re exit(0); 
#define _lower(x) lower_bound(v.begin(),v.end(),x)-v.begin()+1  
 
const int mod = 1e9+7 ; 
const int INF = 1e9 ; 
const int LOG = 18 ; 
 
typedef vector<int> vi ; 
typedef pair<int,int> pii ; 
typedef vector<ll> vl ; 
typedef vector<pii> vii ; 
 
void add ( int &a , int b ) 
{
	a += b ;
	if ( a < 0 ) a += mod ; 
	if ( a >= mod ) 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 ; } 
 
void rf () 
{
	freopen ("bai1.inp","r",stdin) ; 
//	freopen ("bai1.out","w",stdout) ; 
}
 
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 ; 
}
 
int n , m , nq ; 
struct edge {
	int u , v , w ; 
}a[maxn]; 
 
struct query {
	int t , s , w ; 
}q[maxn];
 
const int block = 1000 ; 
 
bool cmp_aw ( int u , int v ) 
{
	return a [u].w > a [v].w ; 
}
bool cmp_qw ( int u , int v ) 
{
	return q [u].w > q [v].w ; 
}
 
int par [maxn] , sz [maxn] , changed [maxn] ; 
 
void reset () 
{
	for ( int i = 1 ; i <= n ; i ++ ) par [i] = i , sz [i] = 1 ; 
	for ( int i = 1 ; i <= m ; i ++ ) changed [i] = false ; 
}
 
vi to_join [maxn] ; 
 
int find ( int u ) 
{
	if ( par [u] == u ) return u ; 
	return find (par[u]) ; 
}
 
int *roll [maxn*2] , val [maxn*2] , top ; 
void update_roll ( int *a , int b ) 
{
	if ( *a == b ) return ; 
	roll [++top] = a ; 
	val [top] = *a ; 
	*a = b ; 
}
void rollback ( int cur ) 
{
	while ( top > cur ) 
	{
		*roll [top] = val [top] ; 
		top -- ; 
	}
}
 
void uni ( int u , int v ) 
{
	int p = find (u) , q = find (v) ; 
	if ( p == q ) return ; 
	if ( sz [p] > sz [q] ) swap (p,q) ; 
	update_roll (&sz[q],sz[p]+sz[q]) ; 
	update_roll (&par[p],q) ; 
}
 
int ans [maxn] ; 
 
int main () 
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);cout.tie(0) ; 
//	rf () ; 
	cin >> n >> m ; 
	for ( int i = 1 ; i <= m ; i ++ ) cin >> a[i].u >> a[i].v >> a[i].w ; 
	cin >> nq ; 
	for ( int i = 1 ; i <= nq ; i ++ ) cin >> q[i].t >> q[i].s >> q[i].w ; 
	
	for ( int l = 1 ; l <= nq ; l += block ) 
	{
		int r = min (nq+1,l+block) - 1 ; 
		reset () ; top = 0 ; 
		vi upd , unchanged , ask ; 
		for ( int i = l ; i <= r ; i ++ ) 
		{
			if ( q[i].t == 1 ) 
			{
				changed[q[i].s] = true ; 
				upd . pb (i) ; 
			}
			else ask . pb (i) ; 
		}
		for ( int i = 1 ; i <= m ; i ++ ) if ( changed [i] == false ) unchanged . pb (i) ; 
		for ( int i = l ; i <= r ; i ++ ) 
		{
			if ( q[i].t == 1 ) 
			{
				a[q[i].s].w = q[i].w ; 
			}
			else 
			{
				for ( auto x : upd ) 
				{
					if ( a[q[x].s].w >= q[i].w ) to_join [i] . pb (q[x].s) ; 
				}
			}
		}
			
		sort (unchanged.begin(),unchanged.end(),cmp_aw) ; 
		sort (ask.begin(),ask.end(),cmp_qw) ; 
		
		int j = 0 ; 
		for ( auto x : ask ) 
		{
			while ( j < unchanged.size() && a[unchanged[j]].w >= q[x].w ) 
			{
				int u = a[unchanged[j]].u , v = a[unchanged[j]].v ; 
				uni (u,v) ; 
				j ++ ; 
			}
			
			int cur = top ; 
			for ( auto y : to_join [x] )
			{
				int u = a[y].u , v = a[y].v ; 
				uni (u,v) ; 
			}
			ans [x] = sz[find(q[x].s)] ; 
			rollback (cur) ; 
		}
		
	}
	for ( int i = 1 ; i <= nq ; i ++ ) if ( q[i].t == 2 ) cout << ans [i] << "\n" ; 
}
 
// range , error , check special , ... 
// find key , find key 
//'-std=c++11' stay hard 
// there is no tomorrow 

Compilation message (stderr)

bridges.cpp: In function 'int main()':
bridges.cpp:156:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  156 |    while ( j < unchanged.size() && a[unchanged[j]].w >= q[x].w )
      |            ~~^~~~~~~~~~~~~~~~~~
bridges.cpp: In function 'void rf()':
bridges.cpp:34:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   34 |  freopen ("bai1.inp","r",stdin) ;
      |  ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 16 / 16
• Subtask 3: 17 / 17
• Subtask 4: 14 / 14
• Subtask 5: 13 / 13
• Subtask 6: 27 / 27