Submission #1133673

#	Time	Username	Problem	Language	Result	Execution time	Memory
1133673		steveonalex	Cat Exercise (JOI23_ho_t4)	C++20	100 / 100	223 ms	43500 KiB

Main

#include <bits/stdc++.h>
 
using namespace std;
 
typedef long long ll;
typedef unsigned long long ull;
 
#define MASK(i) (1LL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
#define block_of_code if(true)
 
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll gcd(ll a, ll b){return __gcd(a, b);}
ll lcm(ll a, ll b){return a / gcd(a, b) * b;}
 
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
 
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
double rngesus_d(double l, double r){
    double cur = rngesus(0, MASK(60) - 1);
    cur /= MASK(60) - 1;
    return l + cur * (r - l);
}
 
template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b) {a = b; return true;}
        return false;
    }
 
template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b) {a = b; return true;}
        return false;
    }
 
template <class T>
    void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
        for(auto item: container) out << item << separator;
        out << finish;
    }
 
template <class T>
    void remove_dup(vector<T> &a){
        sort(ALL(a));
        a.resize(unique(ALL(a)) - a.begin());
    }

struct DSU{
    int n;
    vector<int> parent, sz;
    vector<pair<int, ll>> dp;

    DSU(int _n){
        n = _n;
        parent.resize(n+1); sz.resize(n+1, 1);
        dp.resize(n+1);
        for(int i = 1; i<=n; ++i) {
            parent[i] = i;
            dp[i] = {i, 0};
        }
    }

    int find_set(int u){return (u == parent[u]) ? u : (parent[u] = find_set(parent[u]));}
    bool same_set(int u, int v){return find_set(u) == find_set(v);}

    bool join_set(int u, int v){
        u = find_set(u), v = find_set(v);
        if (u != v){
            if (sz[u] < sz[v]) swap(u, v);
            parent[v] = u;
            sz[u] += sz[v];
            dp[u] = dp[v];
            return true;
        }
        return false;
    }

    int get_size(int u){return sz[find_set(u)];}

    pair<int, ll> get_dp(int u){return dp[find_set(u)];}
    void set_dp(int u, pair<int, ll> v){dp[find_set(u)] = v;}
};

const int N = 2e5 + 69, LOG_N = 18;
int n;
int a[N], p[N];
vector<int> graph[N];
int h[N], parent[N][LOG_N];

void dfs(int u, int p){
    h[u] = h[p] + 1;
    for(int j = 1; MASK(j) < h[u]; ++j) 
        parent[u][j] = parent[parent[u][j-1]][j-1];
    for(int v: graph[u]) if (v != p){
        parent[v][0] = u;
        dfs(v, u);
    }
}

int LCA(int u, int v){
    if (h[u] < h[v]) swap(u, v);
    int diff = h[u] - h[v];
    for(int j = 0; j < LOG_N; ++j) if (GETBIT(diff, j)) 
        u = parent[u][j];
    if (u == v) return u;
    for(int j = LOG_N - 1; j >= 0; --j) if (parent[u][j] != parent[v][j]){
        u = parent[u][j];
        v = parent[v][j];
    }
    return parent[u][0];
}

int path_length(int u, int v){
    return h[u] + h[v] - 2*h[LCA(u, v)];
}

ll solve(){
    cin >> n;
    for(int i = 1; i <= n; ++i) cin >> a[i];
    for(int i = 1; i <= n; ++i) p[a[i]] = i;
    for(int i = 1; i < n; ++i){
        int u, v; cin >> u >> v;
        graph[u].push_back(v);
        graph[v].push_back(u);
    }

    dfs(1, 0);

    DSU mst(n);
    vector<ll> dp(n+1);
    for(int i = 1; i <= n; ++i){
        int u = p[i];
        for(int v: graph[u]) if (a[v] < a[u]){
            pair<int, ll> cur = mst.get_dp(v);
            maximize(dp[i], cur.second + path_length(cur.first, u));
            mst.join_set(u, v);
        }
        mst.set_dp(u, make_pair(u, dp[i]));
    }
    return dp.back();
}

int main(void){
    ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
 
    clock_t start = clock();
 
    cout << solve() << "\n";    
 
    cerr << "Time elapsed: " << clock() - start << "ms!\n";
 
    return 0;
}

• 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