Bitmask DP
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| #include <bits/stdc++.h>
using namespace std;
int N;
vector<vector<int>> adj;
vector<int> prevnum, rating, ans, parent;
int countval = 0;
vector<int> bit;
// bit functions
void updateBIT(int a, int b) {
while (a <= N) { bit[a] += b; a += (a & (-a));}
}
int query(int a) {
int r = 0;
while (a > 0) {r += bit[a]; a = a - (a & (-a));} return r;
}
void dfs(int node) {
prevnum[node] = query(N) - query(rating[node]);
for (auto child : adj[node]) {
countval++;
dfs(child);
}
ans[node] = query(N) - query(rating[node]) - prevnum[node];
updateBIT(rating[node], 1);
}
int main() {
ifstream cin("promote.in");
ofstream cout("promote.out");
cin >> N;
adj.resize(N + 1);
rating.resize(N + 1);
bit.resize(N + 1);
parent.resize(N + 1, -1);
prevnum.resize(N + 1);
ans.resize(N + 1);
vector<pair<int, int>> old(N + 1);
for (int i = 1; i < N + 1; i++) {
cin >> old[i].first;
old[i].second = i;
}
for (int i = 2; i < N + 1; i++) {
int p;
cin >> p;
adj[p].push_back(i);
}
// compression
sort(old.begin(), old.end());
for (int i = 1; i < N + 1; i++) {
rating[old[i].second] = i;
}
dfs(1);
for (int i = 1; i <= N; i++) {
cout << ans[i] << endl;
}
}
|