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P3605 [USACO17JAN]Promotion Counting P

https://www.luogu.com.cn/record/86666473
This commit is contained in:
Baoshuo Ren 2022-09-15 15:41:28 +08:00
parent 3256f5c172
commit f738250c11
Signed by: baoshuo
GPG Key ID: 00CB9680AB29F51A

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Luogu/P3605/P3605.cpp Normal file
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#include <iostream>
#include <algorithm>
#include <vector>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 1e5 + 5;
int n, p[N], c[N], ans[N];
std::vector<int> nums, g[N];
inline int lowbit(int x) {
return x & -x;
}
inline void add(int x, int y) {
for (; x <= n; x += lowbit(x)) c[x] += y;
}
inline int sum(int x) {
int res = 0;
for (; x; x -= lowbit(x)) res += c[x];
return res;
}
void dfs(int u) {
ans[u] -= sum(n) - sum(p[u]);
for (int v : g[u]) {
dfs(v);
}
ans[u] += sum(n) - sum(p[u]);
add(p[u], 1);
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> p[i];
nums.emplace_back(p[i]);
}
std::sort(nums.begin(), nums.end());
nums.erase(std::unique(nums.begin(), nums.end()), nums.end());
for (int i = 1; i <= n; i++) {
p[i] = std::lower_bound(nums.begin(), nums.end(), p[i]) - nums.begin() + 1;
}
for (int i = 2, x; i <= n; i++) {
cin >> x;
g[x].emplace_back(i);
}
dfs(1);
for (int i = 1; i <= n; i++) {
cout << ans[i] << endl;
}
return 0;
}