Submission #943910

#	Time	Username	Problem	Language	Result	Execution time	Memory
943910		vjudge1	Dynamic Diameter (CEOI19_diameter)	C++17	24 / 100	2276 ms	60672 KiB

diameter

#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
//using namespace __gnu_pbds;
 
bool YES(bool f){ if(f) cout << "YES\n" ; else cout << "NO\n" ; return f ; }
void YES(){YES(1);}
void NO(){YES(0);}
void fopn(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);}
//#define ordered_set tree<int, null_type,less_equal<int>, rb_tree_tag,tree_order_statistics_node_update>
#define ios ios_base::sync_with_stdio(0) ; cin.tie(0) ; cout.tie(0);
#define int long long
#define ld long double
#define pii pair <int , int>
#define all(x) x.begin() , x.end()
#define ff first
#define ss second
#define endl '\n'
 
const int N = 3e5 + 5 ;
const int inf = 1e16 ;
const int mod = 1e9 + 8 ;
const double eps = 1e-8 ;
 
template <class T>
bool chmax( T& x , const T& y ){
  bool f = 0 ;
  if ( x < y ) x = y , f = 1 ;
  return f ;
}
template <class T>
bool chmin( T &x , const T &y ){
  bool f = 0 ;
  if ( x > y ) x = y , f = 1 ;
  return f ;
}
 
//code
 
int n , q , w , l ;
int a[N] ;
set <pii> g[N] ;

struct edge{
	int x , y , z ;
};
int mx = -1 , f ;
vector <edge> v ;

void dfs ( int v , int p , int s ){
	//cout << v << ' ' << s << endl ;
	if ( chmax ( mx , s ) ) f = v ;
	for ( auto to : g[v] ){
		if ( to.ff != p ){
			//cout << v << ' ' << to.ff << ' ' << to.ss << endl ;
			dfs ( to.ff , v , s+to.ss ) ;
		}
	}
}

void get(){
	mx = -1 ;
	dfs(1,0,0) ;
	mx = -1 ;
	dfs(f,0,0) ;
	l = mx ;
}

void solve(){
	
	cin >> n >> q >> w ;
	for ( int i = 1 ; i < n ; i ++ ){
		int x , y , z ; cin >> x >> y >> z ;
		g[x].insert({y,z}) ;
		g[y].insert({x,z}) ;
		v.push_back({x,y,z}) ;
	}
	if ( max (n,q) <= 5000 ){
		for ( int i = 0 ; i < q ; i ++ ){
			int a , b ; cin >> a >> b ;
			a = (a+l)%(n-1) ; b = (b+l)%w ;
			g[v[a].x].erase({v[a].y,v[a].z}) ;
			g[v[a].y].erase({v[a].x,v[a].z}) ;
			v[a].z = b ;
			g[v[a].x].insert({v[a].y,v[a].z}) ;
			g[v[a].y].insert({v[a].x,v[a].z}) ;
			get() ;
			cout << l << endl ;
		} return ;
	}
	multiset <int , greater <int>> vec ; 
	for ( auto i : g[1] ) vec.insert(i.ss) ;
	for ( int i = 0 ; i < q ; i ++ ){
		int a , b ; cin >> a >> b ;
			a = (a+l)%(n-1) ; b = (b+l)%w ;
			vec.erase(vec.find(v[a].z)) ;
			v[a].z = b ;
			vec.insert(v[a].z) ;
			auto it = vec.begin() ;
			if ( n == 2 ){
				cout << *it << endl ;
				continue ;
			} it ++ ;
			cout << *vec.begin() + *it << endl ;
	}
}

signed main(){
    ios ;
    int t = 1 ;
    //cin >> t ;
    while ( t -- ) solve() ;
}

Compilation message (stderr)

diameter.cpp: In function 'void fopn(std::string)':
diameter.cpp:10:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   10 | void fopn(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);}
      |                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diameter.cpp:10:72: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   10 | void fopn(string name){freopen((name+".in").c_str(),"r",stdin); freopen((name+".out").c_str(),"w",stdout);}
      |                                                                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 13 / 13
• Subtask 3: 0 / 7
• Subtask 4: 0 / 18
• Subtask 5: 0 / 24
• Subtask 6: 0 / 27