Submission #1125095

#	Time	Username	Problem	Language	Result	Execution time	Memory
1125095		InvMOD	Dynamic Diameter (CEOI19_diameter)	C++20	100 / 100	3183 ms	233052 KiB

diameter

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

#define fi first
#define se second
#define gcd __gcd
#define sz(v) (int) v.size()
#define pb push_back
#define pi pair<int,int>
#define all(v) (v).begin(), (v).end()
#define compact(v) (v).erase(unique(all(v)), (v).end())
#define FOR(i, a, b) for(int i = (a); i <= (b); i++)
#define dbg(x) "[" #x " = " << (x) << "]"
//#define int long long

using ll = long long;
using ld = long double;
using ull = unsigned long long;

template<typename T> bool ckmx(T& a, const T& b){if(a < b) return a = b, true; return false;}
template<typename T> bool ckmn(T& a, const T& b){if(a > b) return a = b, true; return false;}

const int N = 1e5+5;
const ll MOD = 1e9+7;
const ll INF = 1e18;

struct Edge{
    int u,v; ll w;
    Edge(int u = 0, int v = 0, ll w = 0): u(u), v(v), w(w) {}
};

int n, q; ll W;
Edge iE[N]; pair<ll,ll> Q[N];

namespace Subtask12{
    bool checkSubtask(){
        return n <= 5e3 && W <= 10e3;
    }

    const int N = 5e3 + 5;

    int dp[N]; vector<int> adj[N];
    Edge E[N];

    void buildGraph(){
        FOR(i, 1, n-1){
            E[i] = iE[i];
            int u = E[i].u, v = E[i].v;
            adj[u].pb(i), adj[v].pb(i);
        }
    }

    int diameter(int x = 1, int p = -1){
        int answer = 0, mx1 = 0, mx2 = 0;

        dp[x] = 0;
        for(int id : adj[x]){
            int v = E[id].u ^ E[id].v ^ x, w = E[id].w;
            if(v != p){
                answer = max(answer, diameter(v, x));
                dp[x] = max(dp[x], dp[v] + w);

                if(mx1 <= dp[v] + w){
                    mx2 = mx1;
                    mx1 = dp[v] + w;
                }
                else if(mx2 <= dp[v] + w){
                    mx2 = dp[v] + w;
                }
            }
        }

        answer = max(answer, mx1 + mx2);
        return answer;
    }

    void process()
    {
        int last = 0; buildGraph();

        FOR(i, 1, q){
            int dj = (Q[i].fi + last) % (n - 1) + 1;
            int ej = (Q[i].se + last) % W;

            E[dj].w = ej;
            cout << (last = diameter()) <<"\n";
        }
        return;
    }
}

namespace Subtask3{
    bool checkSubtask(){
        int cnt = 0;
        FOR(i, 1, n - 1) cnt += (iE[i].u == 1 || iE[i].v == 1);

        return (cnt == n - 1);
    }

    Edge E[N];

    void process()
    {
        multiset<int> maxW;
        FOR(i, 1, n - 1){
            E[i] = iE[i];
            maxW.insert(E[i].w);
        }

        int last = 0;
        FOR(i, 1, q){
            int dj = (Q[i].fi + last) % (n - 1) + 1;
            int ej = (Q[i].se + last) % W;

            maxW.erase(maxW.find(E[dj].w));
            E[dj].w = ej; maxW.insert(E[dj].w);

            auto it = (--maxW.end());
            last = *it;

            if(it != maxW.begin()){
                --it; last += *it;
            }

            cout << last <<"\n";
        }
        return;
    }
}

struct SMT_POINTMAX{
    int trsz;
    vector<ll> st;

    SMT_POINTMAX(int n = 0): trsz(n), st((n << 2 | 1) + 1) {}

    void init(int n){
        trsz = n;
        st.resize((n << 2 | 1) + 1);
        return;
    }

    void update(int id, int l, int r, int x, ll val){
        if(l == r){
            st[id] = val;
            return;
        }
        else{
            int m = (l+r)>>1;
            if(x <= m) update(id<<1, l, m, x, val);
            else{
                update(id<<1|1, m+1, r, x, val);
            }
            st[id] = max(st[id<<1], st[id<<1|1]);
        }
        return;
    }

    ll answer(){return st[1];}

    void update(int x, ll val){return update(1, 1, trsz, x, val), void();}
};

namespace Subtask4{
    bool checkSubtask()
    {
        FOR(i, 1, n-1){
            if(iE[i].u < iE[i].v){
                if(iE[i].u != (iE[i].v / 2)){
                    return false;
                }
            }
            else{
                if((iE[i].u / 2) != iE[i].v){
                    return false;
                }
            }
        }
        return true;
    }

    int dp[N], par[N];

    multiset<int, greater<int>> maxW[N], answer;
    vector<int> adj[N], g[N], saveDP[N];

    Edge E[N];
    SMT_POINTMAX st;

    void preDFS(int x = 1, int p = -1){

        for(int id : adj[x]){
            int v = E[id].u ^ E[id].v ^ x;
            if(v != p){
                g[x].push_back(v);
                par[v] = id;
                preDFS(v, x);
            }
        }
        sort(all(g[x]));
        saveDP[x].assign(sz(g[x]), -1);
        return;
    }

    void buildGraph(){
        FOR(i, 1, n - 1){
            E[i] = iE[i];
            int u = E[i].u, v = E[i].v;
            if(u > v) swap(E[i].u, E[i].v);

            adj[u].pb(i), adj[v].pb(i);
        }
        return;
    }

    void recalc(int node){
        if(!maxW[node].size()){
            st.update(node, 0);
            return;
        }

        if(maxW[node].size() == 1){
            st.update(node, (*maxW[node].begin()));
        }
        else{
            auto it = maxW[node].begin();
            int last = *it; ++it; last += *it;

            st.update(node, last);
        }
        return;
    }

    void rmv(int x){
        int prenode = x, node = x / 2, curDP = dp[x];
        while(node){
            curDP = curDP + E[par[prenode]].w;

            int id = lower_bound(all(g[node]), prenode) - g[node].begin();

            if(saveDP[node][id] > 0){
                maxW[node].erase(maxW[node].find(saveDP[node][id]));
                saveDP[node][id] = -1;
            }

            prenode = node;
            node = node / 2;
        }
        return;
    }

    void add(int x){
        int prenode = x, node = x / 2, curDP = dp[x];
        while(node){
            curDP = curDP + E[par[prenode]].w;

            // Erase old value (if old value is < new value)
            int id = lower_bound(all(g[node]), prenode) - g[node].begin();

            if(curDP > saveDP[node][id]){
                if(saveDP[node][id] > 0){
                    assert(maxW[node].find(saveDP[node][id]) != maxW[node].end());
                    maxW[node].erase(maxW[node].find(saveDP[node][id]));
                }

                // Add new value
                saveDP[node][id] = curDP;
                maxW[node].insert(curDP);

                // Recalculate
                assert(maxW[node].size());
                recalc(node);
                dp[node] = *maxW[node].begin();
            }
            curDP = dp[node];

            prenode = node;
            node = node / 2;
        }
        return;
    }

    void process()
    {
        buildGraph(), preDFS(); st.init(n);

        FOR(i, 1, n) add(i);

        int last = 0;
        FOR(i, 1, q){
            int dj = (Q[i].fi + last) % (n - 1) + 1;
            int ej = (Q[i].se + last) % W;

            rmv(E[dj].v);
            E[dj].w = ej;
            add(E[dj].v);

            cout << (last = st.answer()) <<"\n";
        }
        return;
    }
}

struct SMT_MAXRANGE{
    int trsz;
    vector<ll> st, laz;

    void init(int n){
        trsz = n;
        st.resize((n << 2 | 1) + 1);
        laz.resize((n << 2 | 1) + 1);
        return;
    }

    void apply(int id, ll val){
        st[id] += val;
        laz[id] += val;
        return;
    }

    void down(int id){
        ll val = laz[id]; laz[id] = 0;
        if(!val) return;
        apply(id<<1, val);
        apply(id<<1|1, val);
        return;
    }

    void update(int id, int l, int r, int u, int v, ll val){
        if(l > v || r < u) return;
        if(l >= u && r <= v){
            apply(id, val);
            return;
        }
        down(id);

        int m = (l+r)>>1;
        update(id<<1, l, m, u, v, val);
        update(id<<1|1, m+1, r, u, v, val);

        st[id] = max(st[id<<1], st[id<<1|1]);
        return;
    }

    ll get(int id, int l, int r, int u, int v){
        if(l > v || r < u) return 0;
        if(l >= u && r <= v) return st[id];

        down(id);
        int m = (l+r)>>1;
        return max(get(id<<1, l, m, u, v), get(id<<1|1, m+1, r, u, v));
    }

    void update(int l, int r, ll val){
        return update(1, 1, trsz, l, r,  val), void();
    }

    ll get(int l, int r){
        return get(1, 1, trsz, l, r);
    }
};

namespace Subtask5{

    SMT_MAXRANGE st;

    int timerDFS, tin[N], tout[N];

    ll depth[N];

    vector<pair<int,ll>> adj[N];
    Edge E[N];

    void preDFS(int x = 1, int p = -1){
        tin[x] = ++timerDFS;
        for(pair<int,ll> e : adj[x]){
            int v = e.fi; ll w = e.se;
            if(v != p){
                depth[v] = depth[x] + w;
                preDFS(v, x);
            }
        }
        tout[x] = timerDFS;
        return;
    }

    void buildGraph()
    {
        FOR(i, 1, n - 1){
            E[i] = iE[i];
            int u = E[i].u, v = E[i].v; ll w = E[i].w;
            adj[u].pb(make_pair(v, w));
            adj[v].pb(make_pair(u, w));
        }
    }

    void process()
    {
        buildGraph();
        preDFS(); st.init(timerDFS);

        FOR(i, 1, n){
            st.update(tin[i], tin[i], depth[i]);
        }

        multiset<ll, greater<ll>> maxW;
        sort(all(adj[1]), [&](pair<int,int> x, pair<int,int> y){return tin[x.fi] < tin[y.fi];});

        vector<int> g; vector<ll> DP;
        for(pair<int,int> v : adj[1]){
            DP.push_back(st.get(tin[v.fi], tout[v.fi]));
            g.push_back(tin[v.fi]);
            maxW.insert(DP.back());
        }

        ll last = 0;
        FOR(i, 1, q){
            ll dj = (Q[i].fi + last) % (n - 1) + 1;
            ll ej = (Q[i].se + last) % W;

            int u = E[dj].u, v = E[dj].v;
            if(tin[u] > tin[v]) swap(u, v);

            st.update(tin[v], tout[v], ej - E[dj].w);
            E[dj].w = ej;

            int id = upper_bound(all(g), tin[v]) - g.begin() - 1;
            int x = adj[1][id].fi;

            assert(id >= 0 && id < (int)g.size());
            assert(maxW.find(DP[id]) != maxW.end());

            maxW.erase(maxW.find(DP[id]));

            DP[id] = st.get(tin[x], tout[x]);
            maxW.insert(DP[id]);

            last = *maxW.begin();
            if(maxW.size() > 1){
                last = last + (*(++maxW.begin()));
            }
            cout << last <<"\n";
        }
        return;
    }
}

namespace Subtask6{

    const int lg = 21;

    // timerDFS
    int timerDFS[lg], tin[lg][N], tout[lg][N];

    // data
    ll depth[lg][N];
    SMT_MAXRANGE st[lg]; SMT_POINTMAX saveCenMax;

    vector<ll> saveDP[N]; vector<ll> idFind[N];
    multiset<ll, greater<ll>> maxD[N];

    // Centroid
    int sz[N], lvl[N], headCen[lg][N]; bool del[N];

    // Tree
    vector<pair<int,ll>> adj[N]; Edge E[N];

    int csz(int x, int p){
        sz[x] = 1;
        for(pair<int,ll> v : adj[x]){
            if(!del[v.fi] && v.fi != p){
                sz[x] += csz(v.fi, x);
            }
        }
        return sz[x];
    }

    int Centroid(int x, int p, int trsz){
        for(pair<int,ll> v : adj[x]){
            if(v.fi != p && !del[v.fi] && sz[v.fi] > trsz / 2) return Centroid(v.fi, x, trsz);
        }
        return x;
    }

    void dfs(int x, int p, int cenID, int lvlCen){
        tin[lvlCen][x] = ++timerDFS[lvlCen];
        headCen[lvlCen][x] = cenID;

        for(pair<int,ll> e : adj[x]){
            int v = e.fi; ll w = e.se;
            if(!del[v] && v != p){
                depth[lvlCen][v] = depth[lvlCen][x] + w;
                dfs(v, x, cenID, lvlCen);
            }
        }
        tout[lvlCen][x] = timerDFS[lvlCen];

        st[lvlCen].update(tin[lvlCen][x], tin[lvlCen][x], depth[lvlCen][x]);
        return;
    }

    void buildCentroid(int x, int direct_parCen){
        x = Centroid(x, -1, csz(x, -1));

        int lvlCen = lvl[direct_parCen] + 1;

        lvl[x] = lvlCen;

        del[x] = true;
        dfs(x, -1, x, lvlCen);

        sort(all(adj[x]), [&](pair<int,ll> x, pair<int,ll> y){
             return tin[lvlCen][x.fi] < tin[lvlCen][y.fi];
        });
        for(pair<int,ll> e : adj[x]){
            int v = e.first;
            saveDP[x].push_back(st[lvlCen].get(tin[lvlCen][v], tout[lvlCen][v]));

            maxD[x].insert(saveDP[x].back());
            idFind[x].push_back(tin[lvlCen][v]);
        }

        for(pair<int,int> v : adj[x]){
            if(!del[v.fi]){
                buildCentroid(v.fi, x);
            }
        }
        return;
    }

    void reCalc(int x){
        if(!maxD[x].size()){
            saveCenMax.update(x, 0);
            return;
        }
        else if(maxD[x].size() == 1){
            saveCenMax.update(x, *maxD[x].begin());
        }
        else{
            ll last = *maxD[x].begin();
            last = last + (*(++maxD[x].begin()));

            saveCenMax.update(x, last);
        }
        return;
    }

    void updateCentroid(int u, int v, ll new_val, ll old_val){
        int curLvl = lg - 1;
        while(curLvl){
            if(headCen[curLvl][u] && headCen[curLvl][u] == headCen[curLvl][v]){
                if(tin[curLvl][u] > tin[curLvl][v]) swap(u, v);

                int x = headCen[curLvl][u];

                int id = upper_bound(all(idFind[x]), tin[curLvl][v]) - idFind[x].begin() -1;

                assert(maxD[x].find(saveDP[x][id]) != maxD[x].end());
                maxD[x].erase(maxD[x].find(saveDP[x][id]));

                st[curLvl].update(tin[curLvl][v], tout[curLvl][v], new_val - old_val);

                int par_v = adj[x][id].fi;
                saveDP[x][id] = st[curLvl].get(tin[curLvl][par_v], tout[curLvl][par_v]);
                maxD[x].insert(saveDP[x][id]);

                reCalc(x);
            }
            curLvl--;
        }
    }

    void preprocess()
    {
        FOR(i, 1, n - 1){
            E[i] = iE[i];
            int u = E[i].u, v = E[i].v; ll w = E[i].w;
            adj[u].pb(make_pair(v, w));
            adj[v].pb(make_pair(u, w));
        }
        FOR(i, 0, lg - 1){
            st[i].init(n);
        }
        saveCenMax.init(n);
        buildCentroid(1, 0);

        FOR(i, 1, n) reCalc(i);
        return;
    }

    void process()
    {
        preprocess();

        ll last = 0;
        FOR(i, 1, q){
            ll dj = (Q[i].fi + last) % (n - 1) + 1;
            ll ej = (Q[i].se + last) % W;

            int u = E[dj].u, v = E[dj].v; ll w = E[dj].w;
            updateCentroid(u, v, ej, w);

            E[dj].w = ej;
            cout << (last = saveCenMax.answer()) <<"\n";
        }
        return;
    }
}

void solve()
{
    cin >> n >> q >> W;
    FOR(i, 1, n-1){
        int a,b; ll c; cin >> a >> b >> c;
        iE[i] = Edge(a, b, c);
    }

    FOR(i, 1, q){
        cin >> Q[i].fi >> Q[i].se;
    }


    return Subtask6::process(), void();
    if(Subtask12::checkSubtask()){
        return Subtask12::process(), void();
    }

    if(Subtask3::checkSubtask()){
        return Subtask3::process(), void();
    }

    if(Subtask4::checkSubtask()){
        return Subtask4::process(), void();
    }

    return Subtask6::process(), void();
    return Subtask5::process(), void();
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);

    #define name "InvMOD"
    if(fopen(name".INP", "r")){
        freopen(name".INP","r",stdin);
        freopen(name".OUT","w",stdout);
    }

    int t = 1; //cin >> t;
    while(t--) solve();
    return 0;
}

Compilation message (stderr)

diameter.cpp: In function 'int main()':
diameter.cpp:648:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  648 |         freopen(name".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
diameter.cpp:649:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  649 |         freopen(name".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