Submission #875650

#	Time	Username	Problem	Language	Result	Execution time	Memory
875650		hmm789	Cat Exercise (JOI23_ho_t4)	C++14	41 / 100	98 ms	53404 KiB

Main

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define INF 1000000000000000000
#define MOD 998244353

int p[200000], spt[200000][18];
vector<int> adj[200000];

int query(int x, int y) {
    int k = (int)floor(log((double)y-x+1)/log(2.0));
    if(p[spt[x][k]] > p[spt[y-(1<<k)+1][k]]) return spt[x][k];
    else return spt[y-(1<<k)+1][k];
}

int dfs(int x, int l, int r) {
    int ans = 0;
    if(x != l) ans = max(ans, dfs(query(l, x-1), l, x-1)+x-query(l, x-1));
    if(x != r) ans = max(ans, dfs(query(x+1, r), x+1, r)+query(x+1, r)-x);
    return ans;
}

int32_t main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    int n, x, y;
    cin >> n;
    for(int i = 0; i < n; i++) cin >> p[i];
    for(int i = 0; i < n-1; i++) {
        cin >> x >> y;
        x--; y--;
        adj[x].push_back(y);
        adj[y].push_back(x);
    }
    for(int i = 0; i < n; i++) spt[i][0] = i;
    for(int j = 1; (1<<j) <= n; j++) {
        for(int i = 0; i + (1<<j) - 1 < n; i++) {
            if(p[spt[i][j-1]] > p[spt[i+(1<<(j-1))][j-1]]) {
                spt[i][j] = spt[i][j-1];
            } else spt[i][j] = spt[i+(1<<(j-1))][j-1];
        }
    }
    cout << dfs(query(0, n-1), 0, n-1);
}

• Subtask 1: 7 / 7
• Subtask 2: 7 / 7
• Subtask 3: 7 / 7
• Subtask 4: 0 / 10
• Subtask 5: 20 / 20
• Subtask 6: 0 / 23
• Subtask 7: 0 / 26