Submission #579209

#	Time	Username	Problem	Language	Result	Execution time	Memory
579209		juggernaut	Dynamic Diameter (CEOI19_diameter)	C++14	24 / 100	5090 ms	10452 KiB

diameter

#include<bits/stdc++.h>
#define fr first
#define sc second
using namespace std;
typedef long long ll;
typedef long double ld;
#define USING_ORDERED_SET 0
#if USING_ORDERED_SET
#include<bits/extc++.h>
using namespace __gnu_pbds;
template<class T>using ordered_set=tree<T,null_type,less<T>,rb_tree_tag,tree_order_statistics_node_update>;
#endif
template<class T>void umax(T &a,T b){if(a<b)a=b;}
template<class T>void umin(T &a,T b){if(b<a)a=b;}
#ifdef juggernaut
    #define printl(args...) printf(args)
#else
    #define printl(args...) 0
#endif
int n,q;
int timer;
ll w[100005];
pair<int,int>edge[100005];
vector<pair<int,int>>g[100005];
bool vis[100005];
int sz[100005];
int par[100005];
int depth[100005];
void build_sz(int v,int p){
	sz[v]=1;
	for(auto &to:g[v])if((to.fr^p)&&(!vis[to.fr])){
		build_sz(to.fr,v);
		sz[v]+=sz[to.fr];
	}
}
int centroid(int v,int p,int sz){
	bool can;
	while(true){
		can=true;
		for(auto &to:g[v])if((to.fr^p)&&(!vis[to.fr])){
			if(::sz[to.fr]>sz){
				can=false;
				p=v;
				v=to.fr;
				break;
			}
		}
		if(can)return v;
	}
}
void build(int v,int p,int dep){
	build_sz(v,0);
	v=centroid(v,0,sz[v]>>1);
	par[v]=p;
	depth[v]=dep;
	vis[v]=true;
	for(auto &to:g[v])if(!vis[to.fr])build(to.fr,v,dep+1);
}
ll ans;
struct SegmentTree{
	vector<ll>vec;
	int n;
	SegmentTree(int _n){
		n=_n;
		vec.assign(n<<2|3,0ll);
	}
};
ll alls[100005];
ll go(int v,int p,int &pivot,ll depth){
	ll mx=depth;
	if(!p){
		ll m1=0,m2=0;
		for(auto &to:g[v])if((to.fr^p)&&::depth[to.fr]>pivot){
			ll cur=go(to.fr,v,pivot,depth+w[to.sc]);
			umax(mx,cur);
			if(cur>m1){
				m2=m1;
				m1=cur;
			}else if(cur>m2)m2=cur;
		}
		mx=m1+m2;
	}else for(auto &to:g[v])if((to.fr^p)&&::depth[to.fr]>pivot)umax(mx,go(to.fr,v,pivot,depth+w[to.sc]));
	return mx;
}
int main(){
	scanf("%d%d%lld",&n,&q,&w[0]);
	for(int i=1;i^n;i++){
		scanf("%d%d%lld",&edge[i].fr,&edge[i].sc,&w[i]);
		g[edge[i].fr].emplace_back(edge[i].sc,i);
		g[edge[i].sc].emplace_back(edge[i].fr,i);
	}
	build(1,0,0);
	for(int i=1;i^n;i++)if(depth[edge[i].fr]>depth[edge[i].sc])swap(edge[i].fr,edge[i].sc);
	for(int i=1;i<=n;i++)alls[i]=go(i,0,depth[i],0);
	while(q--){
		ll x;
		ll y;
		scanf("%lld%lld",&x,&y);
		x=(x+ans)%(n-1)+1;
		y=(y+ans)%w[0];
		//Episode 1-> Think hard
		w[x]=y;
		x=edge[x].fr;
		while(x){
			alls[x]=go(x,0,depth[x],0);
			x=par[x];
		}
		ans=0;
		for(int i=1;i<=n;i++)umax(ans,alls[i]);
		printf("%lld\n",ans);
	}
}

Compilation message (stderr)

diameter.cpp: In function 'int main()':
diameter.cpp:86:7: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   86 |  scanf("%d%d%lld",&n,&q,&w[0]);
      |  ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
diameter.cpp:88:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   88 |   scanf("%d%d%lld",&edge[i].fr,&edge[i].sc,&w[i]);
      |   ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
diameter.cpp:98:8: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   98 |   scanf("%lld%lld",&x,&y);
      |   ~~~~~^~~~~~~~~~~~~~~~~~

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