Submission #1138106

#	Time	Username	Problem	Language	Result	Execution time	Memory
1138106		vuavisao	Election (BOI18_election)	C++20	0 / 100	8 ms	12352 KiB

election

#include <bits/stdc++.h>
#pragma GCC optimize("O3", "unroll-loops")
using namespace std;

using ll = long long;

const int N = 500'000 + 10;

struct LazySegTree {
	struct Node {
		int val = 0;
		int lazy = 0;
		Node() {};
		Node(int _val, int _lazy): val(_val), lazy(_lazy) {};
		Node operator+(const Node& other) const {
			Node res;
			res.val = max(this->val, other.val);
			return res;
		}
	};

	int n_node = 0;
	vector<Node> tree = {};

	void resize(int _n) { n_node = _n; tree.resize((n_node << 2) + 10); };
	LazySegTree() {};
	LazySegTree(int _n) { this->resize(_n); };

	void down(int node, int l, int r) {
		tree[node].val += tree[node].lazy;
		if (l < r) {
			tree[node << 1].lazy += tree[node].lazy;
			tree[node << 1 | 1].lazy += tree[node].lazy;
		}
		tree[node].lazy = 0;
	}

	void update(int node, int l, int r, int L, int R, int val) {
		down(node, l, r);
		if (l > r || L > R || l > R || L > r) return;
		if (L <= l && r <= R) {
			tree[node].lazy += val;
			down(node, l, r);
			return;
		}
		int mid = (l + r) >> 1;
		update(node << 1, l, mid, L, R, val);
		update(node << 1 | 1, mid + 1, r, L, R, val);
		tree[node] = tree[node << 1] + tree[node << 1 | 1];
	}

	void Update(int l, int r, int val) {
		return update(1, 1, n_node, l, r, val);
	}

	Node query(int node, int l, int r, int L, int R) {
		down(node, l, r);
		if (l > r || L > R || l > R || L > r) return Node(-1'000'000'000, 0);
		if (L <= l && r <= R) return tree[node];
		int mid = (l + r) >> 1;
		return query(node << 1, l, mid, L, R) + query(node << 1 | 1, mid + 1, r, L, R);
	}

	Node Query(int l, int r) {
		return query(1, 1, n_node, l, r);
	}
};

struct FenWick {
	int n_node = 0;
	vector<int> tree = {};

	void resize(int n) { n_node = n; tree.resize(n + 10, 0); }
	FenWick() {};
	FenWick(int n) { this -> resize(n); };

	void Update(int idx, int val) {
		for( ; idx <= n_node; idx += (idx & - idx)) tree[idx] += val;
		return;
	}

	int Query(int idx) {
		int res = 0;
		for( ; idx > 0; idx -= (idx & - idx)) res += tree[idx];
		return res;
	}

	int Sum_to(int l, int r) {
		if(l > r) return 0;
		return Query(r) - Query(l - 1);
	}

	int kth(int val) {
		int res = 0, s = 0;
		for(int mask = 30; mask >= 0; -- mask) {
			int nxt = res | (1 << mask);
			if(nxt < n_node && s + tree[nxt] < val) {
				res = nxt;
				s += tree[nxt];
			}
		}
		++ res; return res;
	}

	void reset(int idx) {
		for ( ; idx <= n_node; idx += (idx & - idx)) tree[idx] = 0;
		return;
	}
};

int n, q;
string s;

int pred[N];
vector<pair<int, int>> events[N];
int lft[N];

int res[N];

void solve() {
	cin >> n >> s; s = ' ' + s;
	for (int i = 1; i <= n; ++i) {
		pred[i] = pred[i - 1] + (s[i] == 'C' ? 1 : -1);
	}
	stack<int> stk;
	for (int i = n; i >= 1; --i) {
		if (s[i] == 'T') {
			stk.push(i);
		} else {
			if (!stk.empty()) {
				lft[stk.top()] = i;
				stk.pop();
			}
		}
	}
	while (!stk.empty()) {
		stk.pop();
	}
	LazySegTree st(n);
	for (int i = 1; i <= n; ++i) {
		st.Update(i, i, pred[i]);
	}
	cin >> q;
	for (int i = 1; i <= n; ++i) {
		if (lft[i] != 0) {
			events[lft[i]].push_back(make_pair(i, -1));
		}
	}
	for (int i = 1; i <= q; ++i) {
		int l, r; cin >> l >> r;
		events[l].push_back(make_pair(r, i));
	}
	FenWick bit(n);
	for (int l = n; l >= 1; --l) {
		if (s[l] == 'T') {
			stk.push(l);
			st.Update(l, n, 1);
			bit.Update(l, 1);
			if (lft[l] > 0) {
				bit.Update(lft[l], -1);
			}
		}

		for (const auto& [r, idx] : events[l]) {
			if (idx == -1) {
				st.Update(r, n, -1);
			} else {
				int max_pref = max(pred[l - 1], st.Query(l, r - 1).val);
				// cerr << idx << ' ' << max_pref << ' ' << st.Query(r, r).val << '\n';
				res[idx] = bit.Sum_to(l, r) + max(0, max_pref - st.Query(r, r).val);
			}
		}
	}
	for (int i = 1; i <= q; ++i) {
		cout << res[i] << '\n';
	}
}

int32_t main() {
	std::ios_base::sync_with_stdio(false);
	std::cin.tie(nullptr); std::cout.tie(nullptr);
	// int t; cin >> t;
	int t = 1;
	while (t-- > 0) {
		solve();
		// cout << '\n';
	}
	return (0 ^ 0);
}

/// Code by vuavisao

• Subtask 1: 0 / 28
• Subtask 2: 0 / 54
• Subtask 3: 0 / 18