Submission #799694

#	Time	Username	Problem	Language	Result	Execution time	Memory
799694		farhan132	Cat Exercise (JOI23_ho_t4)	C++17	100 / 100	306 ms	61972 KiB

Main

/***Farhan132***/
// #pragma GCC optimize("Ofast,fast-math")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma")
// #pragma GCC optimization ("unroll-loops")

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef double dd;
typedef pair<ll , ll> ii;
typedef tuple < ll,  ll, ll > tp;
 
#define ff first
#define ss second
#define pb push_back
#define in insert
#define bug printf("**!\n")
#define mem(a , b) memset(a, b ,sizeof(a))
#define front_zero(n) __builtin_clz(n)
#define back_zero(n) __builtin_ctzll(n)
#define total_one(n) __builtin_popcount(n)
#define clean fflush(stdout)
 
const ll mod =  (ll) 998244353;
// const ll mod =  (ll) 1e9 + 7;
//const ll INF = numeric_limits<ll>::max()-1;
const ll INF = (ll)2e18;
 
// ll dx[]={0,1,0,-1};
// ll dy[]={1,0,-1,0};
// ll dxx[]={0,1,0,-1,1,1,-1,-1};
// ll dyy[]={1,0,-1,0,1,-1,1,-1};
 
mt19937 rng(chrono::system_clock::now().time_since_epoch().count());
 
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
 
template <typename T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

const ll N = 2e5 + 5;

ll dp[N];
vector < ll > v[N];

const ll LG = 19;
ll par[LG][N],  depth[N];
void dfs_LCA(ll s, ll p, ll d){
   depth[s] = d;
   par[0][s] = p;
   for(ll i = 1; i < LG; i++){
      par[i][s] = par[i - 1][par[i - 1][s]];
   }
   for(auto u : v[s]){
      if(u - p){
       dfs_LCA(u , s, d + 1);
      }
   }
   return;
}

ll lca(ll a, ll b){
   if(depth[a] > depth[b]) swap(a, b);
   for(ll i = LG - 1; i >= 0; i--){
      if(depth[b] - (1 << i) >= depth[a]) b = par[i][b];
   }
   if(a == b) return a;
   for(ll i = LG - 1; i >= 0; i--){
      if(par[i][a] != par[i][b]) a = par[i][a], b = par[i][b];
   }
   return par[0][a];
}
ll dist(ll a, ll b){
   return depth[a] + depth[b] - 2*depth[lca(a, b)];
}
ll lift(ll a, ll x){
   for(ll i = LG - 1; i >= 0; i--){
      if((x >> i)&1) a = par[i][a];
   }
   return a;
}
ll kth(ll a, ll b, ll k){
   ll d = dist(a, b);
   assert(k <= d);
   ll L = lca(a, b);
   if(depth[a] - depth[L] >= k){
      return lift(a, k);
   }
   return lift(b, d - k);
}

struct DSU{
    vector < int > par;
    vector < int > mx;
    void start(int n){
        par.resize(n + 1);
        mx.resize(n + 1);
        for(int i = 0; i <= n; i++) par[i] = i, mx[i] = i;
    }
    int find(int a){
        if(a == par[a]) return a;
        return par[a] = find(par[a]);
    }
    void merge(int x, int y){
        x = find(x); y = find(y);
        if(x == y) return;
        par[x] = y;
        mx[y] = max(mx[y], mx[x]);
        return;
    }
}T;

ll p[N], c[N];

void solve(){

    ll n; cin >> n;

    for(ll i = 1; i <= n; i++){
        cin >> p[i];
    }

    for(ll i = 1; i < n; i++){
        ll x, y; cin >> x >> y;
        x = p[x]; y = p[y];
        v[x].pb(y);
        v[y].pb(x);
    }

    dfs_LCA(1, 0, 1);
    T.start(n + 1);
    mem(c, 0);


    for(ll i = 1; i <= n; i++){
        c[i] = 1;
        dp[i] = 0;
        for(auto u : v[i]){
            if(c[u]){
                ll n1 = T.mx[T.find(u)];
                dp[i] = max(dp[i], dp[n1] + dist(n1, i));
                T.merge(i, u);
            }
        }
    }
    cout << dp[n] << '\n';


    
   return;
}

int main() {

    #ifdef LOCAL
        freopen("in.txt", "r", stdin);
        freopen("out.txt", "w", stdout);
        auto start_time = clock();
    #else
         // freopen("subsequence.in", "r", stdin);
         // freopen("subsequence.out", "w", stdout); 
         ios_base::sync_with_stdio(0); cin.tie(NULL); cout.tie(NULL);
    #endif

    //precalc();
 
    ll T = 1, CT = 0;// cin >> T; 
 
    while(T--){
        // cout << "Case #" << ++CT << ": ";
        solve();
    }
    
    #ifdef LOCAL
        auto end_time = clock();
        cerr<< "Execution time: "<<(end_time - start_time)*(int)1e3/CLOCKS_PER_SEC<<" ms\n";
    #endif
 
    return 0;
} 

Compilation message (stderr)

Main.cpp: In function 'int main()':
Main.cpp:170:15: warning: unused variable 'CT' [-Wunused-variable]
  170 |     ll T = 1, CT = 0;// cin >> T;
      |               ^~

• Subtask 1: 7 / 7
• Subtask 2: 7 / 7
• Subtask 3: 7 / 7
• Subtask 4: 10 / 10
• Subtask 5: 20 / 20
• Subtask 6: 23 / 23
• Subtask 7: 26 / 26