Submission #1104746

#	Time	Username	Problem	Language	Result	Execution time	Memory
1104746		mohammadsam	Dynamic Diameter (CEOI19_diameter)	C++17	49 / 100	5056 ms	27768 KiB

diameter

/*
    in the name of god
*/
//#pragma GCC optimize("Ofast,O3,unroll-loops")
//#pragma GCC target("avx,avx2,fma")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4.1,sse4.2,sse4a,avx,avx2,popcnt,tune=native")

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

typedef pair<int,int> pii;
typedef pair<long long ,long long> pll;
typedef long long ll ;

#define File          freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
#define md(x)         (((x%MD)+MD)%MD)
#define all(V)        V.begin(),V.end()
#define setprec(x)    fixed << setprecision(x)
#define Mp(a,b)       make_pair(a,b)
#define len(V)        (int)(V.size())
#define sep           ' '
#define endl          '\n'
#define pb(x)         push_back(x)
#define fi            first
#define sec           second
#define popcount(x)   __builtin_popcount(x)
#define lid           u<<1
#define rid           (lid)|1
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

const ll N = 1e5 + 10,SQ=320,LOG=31;
const ll inf = 2e9 , MD = 1e9 + 7;
int n ,q,W;
int dis[N];
int st[N],ft[N],ind[N],tim=1;
int par[N];
vector<pii> g[N];
struct node{
    int sum=1,lazy=1,ind=-1;
    node(int s,int l,int i){sum = s,lazy = l,ind=i;}
    node(){}
};
node seg[N<<2];
node merge(node a,node b){
    node ans ;
    if(a.sum > b.sum) ans = node(a.sum,0,a.ind);
    else ans = node(b.sum,0,b.ind);
    return ans;
}
void shift(int u,int l,int r,int x){
    seg[u].sum += x;
    seg[u].lazy += x;
}
void relax(int u,int l,int r){
    int mid = (l+r)>>1;
    shift(lid,l,mid,seg[u].lazy);
    shift(rid,mid,r,seg[u].lazy);
    seg[u].lazy = 0;
}
void build(int u=1,int l=1,int r=n+1){
    if(r-l==1){
        seg[u].sum = seg[u].lazy = 0;
        seg[u].sum = dis[ind[l]];
        seg[u].ind = l;
        return ;
    }
    int mid = (l+r)>>1;
    build(lid,l,mid);
    build(rid,mid,r);
    seg[u] = merge(seg[lid],seg[rid]);
}
void update(int s,int e,int v,int u=1,int l=1,int r=n+1){
    if(e <= l || e <= l || r <= s) return ;
    if(s <= l and r <= e){
        shift(u,l,r,v);
        return ;
    }
    int mid = (l+r)>>1;
    relax(u,l,r);
    update(s,e,v,lid,l,mid);
    update(s,e,v,rid,mid,r);
    seg[u] = merge(seg[lid],seg[rid]);
}
node get(int s,int e,int u=1,int l=1,int r=n+1){
    if(e <= s) return node(-inf,0,0);
    if(s <= l and r <= e) return seg[u];
    int mid = (l+r)>>1;
    relax(u,l,r);
    if(e <= mid) return get(s,e,lid,l,mid);
    if(s >= mid) return get(s,e,rid,mid,r);
    return merge(get(s,e,lid,l,mid),get(s,e,rid,mid,r));
}
pair<pii,int> E[N];
void dfs(int u,int p,int w){
    st[u] = tim++;
    par[u] = p;
    dis[u] = (u==p ? 0 : dis[p] + w);
    ind[st[u]] = u;
    for(auto h : g[u]){
        if(h.fi != p){
            dfs(h.fi,u,h.sec);
        }
    }
    ft[u] = tim;
}


int mx[N];
int32_t main() {
    ios_base::sync_with_stdio(false);cout.tie(0);cin.tie(0);
    cin >> n >> q >> W;
    for(int i = 0;i<n-1;i++){
        int u,v,w;
        cin >> u >> v >> w;
        E[i] = Mp(Mp(u,v),w);
        g[u].pb(Mp(v,w));
        g[v].pb(Mp(u,w));
    }
    int lst = 0;
    dfs(1,1,0);
    build();
    
    for(int i = 0;i<q;i++){
        int e,s;
        cin >> e >> s;
        e = (e+lst)%(n-1);
        s = (s+lst)%W;
        pair<pii,int> pp = E[e];
        auto [u,v] = pp.fi;
        if(par[v] == u) swap(u,v);
        update(st[u],ft[u],s-E[e].sec);
        E[e].sec = s;
        node p = seg[1];
        int who = ind[p.ind];
        int now = who;
        int ans = 0;
        int ls = -1; 
        while(1){
            int tmp = get(st[who],st[who]+1).sum - 2*get(st[now],st[now]+1).sum;
            if(ls == -1){
                tmp += get(st[now],ft[now]).sum;
            }
            else{
                int oo = max(get(st[now],st[ls]).sum,get(ft[ls],ft[now]).sum);
                tmp += oo;
            }
            ans = max(ans,tmp);
            if(now == 1) break;
            ls = now;
            now = par[now];
        }
        cout << ans << endl;
        lst = ans;
    }

    return 0;
}

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