Submission #1178110

#	Time	Username	Problem	Language	Result	Execution time	Memory
1178110		ByeWorld	Dynamic Diameter (CEOI19_diameter)	C++20	42 / 100	5093 ms	63836 KiB

diameter

#include <bits/stdc++.h>
// #pragma GCC optimize("O3")
// #define int long long
#define ll long long
#define pb push_back
#define fi first
#define se second
#define lf (id<<1)
#define rg ((id<<1)|1)
#define md ((l+r)>>1)
#define ld long double
using namespace std;
typedef pair<int,int> pii;
typedef pair<int,pii> ipii;
const int MAXN = 1e6+10;
const int MAXA = 1e9;
const int INF = 1e9+100;
const int SQRT = 500;
const int LOG = 61;
const int MOD = 1e9+7;
void chmn(auto &a, auto b){ a = min(a, b); }
void chmx(auto &a, auto b){ a = max(a, b); }
int sum(int a, int b){ a %= MOD; b %= MOD; return (a+b)%MOD; }
void chsum(int &a, int b){ a %= MOD; b %= MOD; a = (a+b)%MOD; }
void chsub(int &a, int b){ a %= MOD; b %= MOD; a = (a+MOD-b)%MOD; }
int mul(int a, int b){ a %= MOD; b %= MOD; return a*b%MOD;}
void chmul(int &a, int b){ a = a*b%MOD; }
int expo(int a, int b){
	if(b==0) return 1;
	int te = expo(a, b/2); te = mul(te, te);
	return (b%2 ? mul(te, a) : te);
}

int leaf[MAXN];
struct segtree {
	int st[4*MAXN], laz[4*MAXN];
	void bnc(int id, int l, int r){
		if(laz[id]==0) return;
		st[lf] += laz[id]; laz[lf] += laz[id];
		st[rg] += laz[id]; laz[rg] += laz[id];
		laz[id] = 0; 
	}
	void bd(int id,int l,int r){
		if(l==r){ st[id] = leaf[l]; return; }
		bd(lf,l,md); bd(rg,md+1,r);
		st[id] = max(st[lf], st[rg]);
	}
	int que(int id,int l,int r,int x,int y){
		if(x<=l && r<=y) return st[id];
		if(r<x || y<l) return -INF;
		bnc(id,l,r);
		return max(que(lf,l,md,x,y), que(rg,md+1,r,x,y));
	}
	int upd(int id,int l,int r,int x,int y,int p){
		if(x<=l && r<=y){
			laz[id] += p;
			return st[id] += p;
		}
		if(r<x || y<l) return st[id];
		bnc(id,l,r);
		return st[id] = max(upd(lf,l,md,x,y,p), upd(rg,md+1,r,x,y,p));
	}
} A;

int n, q, W;
int u[MAXN], v[MAXN], w[MAXN], par[MAXN];
vector<pii> tree[MAXN], adj[MAXN];

int val[MAXN], tim, in[MAXN], out[MAXN];
void dfs(int nw, int pa){
	in[nw] = ++tim;
	par[nw] = pa; 
	for(auto [nx,wei] : tree[nw]){
		if(nx==pa) continue;
		adj[nw].pb({nx, wei});
		val[nx] = val[nw]+wei;
		dfs(nx,nw);
	}
	out[nw] = tim; leaf[in[nw]] = val[nw];
}
int opt[MAXN];
multiset<int>m;
void trav(int nw){
	int mx = 0, mx2 = 0;
	for(auto [nx, wei] : adj[nw]){
		int te = A.que(1,1,n,in[nx],out[nx]);
		if(te >= mx) mx2 = mx, mx = te;
		else if(te >= mx2) mx2 = te;
	}
	opt[nw] = mx+mx2 - 2*A.que(1,1,n,in[nw],in[nw]); 

	m.insert(opt[nw]);
	// cout << nw << ' ' << opt[nw] << " opt\n";

	for(auto [nx, wei] : adj[nw])
		trav(nx);
}
void UPD(int nw){
	if(nw==0) return;

	m.erase(m.find(opt[nw]));
	int mx = 0, mx2 = 0;
	for(auto [nx, wei] : adj[nw]){
		int te = A.que(1,1,n,in[nx],out[nx]);
		if(te >= mx) mx2 = mx, mx = te;
		else if(te >= mx2) mx2 = te;
	}
	opt[nw] = mx+mx2 - 2*A.que(1,1,n,in[nw],in[nw]); 
	m.insert(opt[nw]);

	UPD(par[nw]);
}
signed main(){
	ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
	cin>>n>>q>>W;
	for(int i=1; i<=n-1; i++){
		int x,y,we; cin>>x>>y>>we; 
		tree[x].pb({y,we}); tree[y].pb({x,we});
		u[i] = x; v[i] = y; w[i] = we;
	}
	dfs(1,0);
	for(int i=1; i<=n-1; i++)
		if(par[u[i]] == v[i]) swap(u[i], v[i]);
	A.bd(1,1,tim);
	trav(1);

	int P = 0;
	while(q--){
		int x,y; cin>>x>>y;
		x = (x+P)%(n-1)+1; y = (y+P)%W;
		// cout << x << ' ' << y << " xy\n";

		int baw = v[x];
		A.upd(1,1,tim,in[baw],out[baw], y-w[x]);
		UPD(u[x]);
		// for(auto p : m) cout << p << " p\n";
		w[x] = y;
		cout << *(--m.end()) << '\n';

		P = *(--m.end());
	}
}

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