Create haircut.cpp

Changes

1 changed files (+59/-0)

• 2020/US Open/Gold/haircut.cpp (new)
  • @@ -0,0 +1,59 @@
    + #include <bits/stdc++.h> + using namespace std; + typedef long long ll; + + template<typename T> class fenwick_tree { + private: vector<T> FT; + public: + fenwick_tree(int N) { FT.assign(N + 1, 0); } + void update(int x, T val) { if (x > 0) for (; x < FT.size(); x += x & -x) FT[x] += val; } + T query(int x) { T ret = 0; if (x > 0) for (; x > 0; x -= x & -x) ret += FT[x]; return ret; } + T query(int x, int y) { return query(y) - query(x - 1); } + }; + + ll N, seg[400004] = { 0 }, tmp[400004] = { 0 }; + inline ll pull(const ll& l, const ll& r) { return l + r; } + inline void push(int l, int r, int n) { + seg[n] += (r - l + 1) * tmp[n]; + if (l != r) tmp[n << 1] += tmp[n], tmp[n << 1 | 1] += tmp[n]; + tmp[n] = 0; + } + void update(int a, int b, ll v, int l = 0, int r = -1, int n = 1) { + if (r == -1) r = N - 1; + push(l, r, n); + if (l > b || r < a) return; + if (l >= a && r <= b) { + tmp[n] += v; + push(l, r, n); + } + else { + int m = (l + r) >> 1; + update(a, b, v, l, m, n << 1), update(a, b, v, m + 1, r, n << 1 | 1); + seg[n] = pull(seg[n << 1], seg[n << 1 | 1]); + } + } + ll query(int a, int b, int l = 0, int r = -1, int n = 1) { + if (r == -1) r = N - 1; + if (a > b || l > b || r < a) return 0; + push(l, r, n); + if (l >= a && r <= b) return seg[n]; + int m = (l + r) >> 1; + return pull(query(a, b, l, m, n << 1), query(a, b, m + 1, r, n << 1 | 1)); + } + + int A[100001]; + + int main() { + ifstream cin("haircut.in"); + ofstream cout("haircut.out"); + + cin >> N; + for (int i = 0; i < N; ++i) cin >> A[i]; + + fenwick_tree<ll> FT(N); + for (int i = 0; i < N; ++i) { + update(A[i] + 1, N, FT.query(A[i] + 1, N)); + FT.update(A[i], 1); + } + for (int i = 0; i < N; ++i) cout << query(i, i) << '\n'; + }