Submission #571986

#	Time	Username	Problem	Language	Result	Execution time	Memory
571986		Shin	Election (BOI18_election)	C++14	100 / 100	565 ms	46464 KiB

election

#include <bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define all(x) x.begin(), x.end()

using namespace std;
template <class X, class Y> bool minimize(X &a, Y b) {
    if (a > b) return a = b, true;
    return false;
}
template <class X, class Y> bool maximize(X &a, Y b) {
    if (a < b) return a = b, true;
    return false;
}

struct segment_tree {
  struct Node {
    int sum, ans;
    Node(int _sum = 0, int _ans = 0) {
      sum = _sum;
      ans = _ans;
    }
    Node operator + (const Node &oth) const {
      return Node(sum + oth.sum, min(oth.ans, ans + oth.sum));
    }
  };

  vector<Node> t;
  int n;
  segment_tree(int _n) : n(_n) {
    t.resize((n << 2) + 7);
  }

  void modify(int node, int l, int r, int p, int v) {
    if (l > p || r < p) {
      return;
    }
    if (l == r) {
      t[node] = Node(v, v);
    } else {
      int mid = (l + r) >> 1;
      modify(node << 1, l, mid, p, v);
      modify(node << 1|1, mid + 1, r, p, v);
      t[node] = t[node << 1] + t[node << 1|1];
    }
  }

  Node get(int node, int l, int r, int u, int v) {
    if (l > v || r < u) {
      return Node(0, 0);
    }
    if (u <= l && r <= v) {
      return t[node];
    }
    int mid = (l + r) >> 1;
    Node L = get(node << 1, l, mid, u, v);
    Node R = get(node << 1|1, mid + 1, r, u, v);
    return L + R;
  }

  void modify(int p, int v) {
    modify(1, 1, n, p, v);
  }

  int get(int l, int r) {
    return -get(1, 1, n, l, r).ans;
  }
};

const int N = 5e5 + 7;

int n;
int a[N];
int res[N];
string s;

vector<pair<int, int>> pos[N];

signed main() {
  cin.tie(0)->sync_with_stdio(0);
  cin >> n >> s;
  for (int i = 1; i <= n; i ++) {
    a[i] = (s[i - 1]  == 'C' ? 1 : -1);
  }
  int q; cin >> q;
  for (int i = 1; i <= q; i ++) {
    int l, r; cin >> l >> r;
    pos[l].emplace_back(r, i);
  }
  vector<int> s;
  segment_tree st(n);
  for (int l = n; l > 0; l --) {
    if (a[l] == 1) {
      if (!s.empty()) {
        st.modify(-s.back(), -1);
        s.pop_back();
      }
      st.modify(l, 1);
    } else {
      s.push_back(-l);
    }
    for (pair<int, int> x: pos[l]) {
      int r, i; tie(r, i) = x;
      int add = lower_bound(all(s), - r) - s.begin();
      add = (int) s.size() - add;
      res[i] = max(0, st.get(l, r)) + add;
    }
  }
  for (int i = 1; i <= q; i ++) {
    cout << res[i] << '\n';
  }
  return 0;
}

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