Submission #1150232

#	Time	Username	Problem	Language	Result	Execution time	Memory
1150232		trandangquang	Dynamic Diameter (CEOI19_diameter)	C++20	100 / 100	3103 ms	217312 KiB

diameter

#include <bits/stdc++.h>
using namespace std;

#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)
#define sz(a) (int)(a).size()
#define all(a) (a).begin(), (a).end()
#define bit(s, i) (((s) >> (i)) & 1)
#define ii pair <int, int>
#define fi first
#define se second
#define ll long long
#define eb emplace_back
#define pb push_back
#define __builtin_popcount __builtin_popcountll

template <class X, class Y>
    bool maximize(X &x, Y y) {
        if(x < y) {
            x = y;
            return true;
        }
        return false;
    }

template <class X, class Y>
    bool minimize(X &x, Y y) {
        if(x > y) {
            x = y;
            return true;
        }
        return false;
    }

void solve();
int32_t main() {
    #define task "test"
    if(fopen(task".inp", "r")) {
		freopen(task".inp", "r", stdin);
		freopen(task".out", "w", stdout);
	}
	cin.tie(0)->sync_with_stdio(0);

    solve();
}

const int N=1e5+5;

int n,q,sz[N]; ll wmx,last,d[N];
bool del[N];
vector<pair<int,ll>> adj[N];
pair<ii,ll> edl[N];
multiset<ll> dia;
vector<ii> anc[N];

int getSize(int u, int p=-1){
    sz[u]=1;
    for(auto [v,w]:adj[u]) if(v!=p && !del[v]){
        sz[u]+=getSize(v,u);
    }
    return sz[u];
}
int getCen(int u, int szAll, int p=-1){
    for(auto [v,w]:adj[u]) if(v!=p && !del[v]){
        if(sz[v]>szAll/2) return getCen(v,szAll,u);
    }
    return u;
}
struct Tree{
    int root,num,Time;
    vector<int> tout,up,near;
    vector<ii> ver;
    vector<ll> lz,st,valnear;
    multiset<ll> road;

    void dfs(int u, int p=-1){
        int tin=++Time;
        anc[u].eb(root,tin);
        ver.eb(u,tin);
        for(auto [v,w]:adj[u]) if(v!=p && !del[v]){
            if(p==-1){
                up[Time+1]=Time+1;
                near.eb(Time+1);
            }
            else up[Time+1]=up[tin];
            d[Time+1]=d[tin]+w;
            dfs(v,u);
        }
        tout[tin]=Time;
    }
    void build(int id, int l, int r){
        if(l==r){
            st[id]=d[l];
            return;
        }
        int mid=(l+r)>>1;
        build(id<<1,l,mid);
        build(id<<1|1,mid+1,r);
        st[id]=max(st[id<<1],st[id<<1|1]);
    }
    void down(int id){
        if(lz[id]==0) return;
        st[id<<1]+=lz[id];
        st[id<<1|1]+=lz[id];
        lz[id<<1]+=lz[id];
        lz[id<<1|1]+=lz[id];
        lz[id]=0;
    }
    ll get(int u, int v, int id, int l, int r){
        if(u>r||v<l) return 0;
        if(u<=l&&r<=v) return st[id];
        down(id);
        int mid=(l+r)>>1;
        return max(get(u,v,id<<1,l,mid),get(u,v,id<<1|1,mid+1,r));
    }
    void start(int r, int node){
        root=r; num=node;
        tout.resize(node+5);
        lz.resize((node<<2)+5);
        st.resize((node<<2)+5);
        up.resize(node+5);
        valnear.resize(node+5);
        dfs(root);
        build(1,1,node);
        for(int i:near){
            road.insert(valnear[i]=get(i,tout[i],1,1,node));
        }
        auto it2=prev(road.end());
        if(sz(road)==1) dia.insert(*it2);
        else dia.insert(*it2+*prev(it2));

        sort(all(ver));
    }
    void add(int u, int v, ll val, int id, int l, int r){
        if(u>r||v<l) return;
        if(u<=l&&r<=v){
            st[id]+=val;
            lz[id]+=val;
            return;
        }
        down(id);
        int mid=(l+r)>>1;
        add(u,v,val,id<<1,l,mid);
        add(u,v,val,id<<1|1,mid+1,r);
        st[id]=max(st[id<<1],st[id<<1|1]);
    }
    void upd(int v, ll w, int id){
        int idu=id,idv;

        auto it=lower_bound(all(ver),make_pair(v,0));
        if(it==ver.end()||(*it).fi!=v) return;
        idv=(*it).se;

        if(idu>idv) swap(idu,idv);

        auto it2=prev(road.end());
        if(sz(road)==1) dia.erase(dia.find(*it2));
        else dia.erase(dia.find(*it2+*prev(it2)));

        road.erase(road.find(valnear[up[idv]]));
        add(idv,tout[idv],w,1,1,num);
        valnear[up[idv]]=get(up[idv],tout[up[idv]],1,1,num);
        road.insert(valnear[up[idv]]);

        ll val;
        it2=prev(road.end());
        if(sz(road)==1) dia.insert(val=*it2);
        else dia.insert(val=*it2+*prev(it2));
    }
} tree[N];
void decomp(int u){
    int cen=getCen(u,getSize(u));

    del[cen]=1;
    if(sz[u]>1) tree[cen].start(cen,sz[u]);

    for(auto [v,w]:adj[cen]) if(!del[v]) decomp(v);
}

void solve() {
    cin>>n>>q>>wmx;
    FOR(i,1,n-1){
        int u,v; ll c; cin>>u>>v>>c;
        edl[i]={{u,v},c};
        adj[u].eb(v,c);
        adj[v].eb(u,c);
    }
    decomp(1);

    FOR(i,1,q){
        int d; ll e; cin>>d>>e;
        d=(d+last)%(n-1);
        e=(e+last)%wmx;

        ll change=e-edl[d+1].se;
        edl[d+1].se=e;
        for(auto [j,id]:anc[edl[d+1].fi.fi]){
            tree[j].upd(edl[d+1].fi.se,change,id);
        }
        cout<<*prev(dia.end())<<'\n';
        last=*prev(dia.end());
    }
}

Compilation message (stderr)

diameter.cpp: In function 'int32_t main()':
diameter.cpp:39:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   39 |                 freopen(task".inp", "r", stdin);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
diameter.cpp:40:24: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |                 freopen(task".out", "w", stdout);
      |                 ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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