Submission #195677

#	Time	Username	Problem	Language	Result	Execution time	Memory
195677		AlexPop28	Election (BOI18_election)	C++11	0 / 100	2 ms	376 KiB

election

#include <bits/stdc++.h>
#define dbg() cerr <<
#define name(x) (#x) << ": " << (x) << ' ' <<

using namespace std;

// aintul interativ e baza.. poate ca nu
struct SegmTree {
  struct Node {
    int sum, min_suf;
    Node(int val = 0) : sum(val), min_suf(min(0, val)) {}
    Node(int sum_, int min_suf_) : sum(sum_), min_suf(min_suf_) {}
  };
  int n;
  vector<Node> tree;
  SegmTree(int n_) : n(n_), tree(4 * n) {}
  Node Join(Node l, Node r) {
    return {l.sum + r.sum,
            min(l.min_suf + r.sum, r.min_suf)};
  }
  void Update(int node, int left, int right, int pos, int val) {
    if (left == right) {
      tree[node] = Node(val);
      return;
    }
    int mid = left + (right - left) / 2;
    if (pos <= mid) {
      Update(2 * node + 1, left, mid, pos, val);
    } else {
      Update(2 * node + 2, mid + 1, right, pos, val);
    }
    tree[node] = Join(tree[2 * node + 1], tree[2 * node + 2]);
  }
  void Update(int pos, int val) {
    Update(0, 0, n - 1, pos, val);
  }
  Node Query(int node, int left, int right, int x, int y) {
    if (x <= left && right <= y) {
      return tree[node];
    }
    int mid = left + (right - left) / 2;
    Node l, r;
    if (x <= mid) {
      l = Query(2 * node + 1, left, mid, x, y);
    }
    if (mid < y) {
      r = Query(2 * node + 2, mid + 1, right, x, y);
    }
    return Join(l, r);
  }
  int Query(int l, int r) {
    return min(Query(0, 0, n - 1, l, r).min_suf, 0);
  }
//  void Update(int pos, int val) {
//    for (tree[pos += n] = Node(val); pos /= 2; ) {
//      tree[pos] = Join(tree[2 * pos], tree[2 * pos + 1]);
//    }
//  }
//  int Query(int l, int r) {
//    ++r;
//    Node ans_left, ans_right;
//    for (l += n, r += n; l < r; l /= 2, r /= 2) {
//      if (l & 1) ans_left  = Join(ans_left,  tree[l++]);
//      if (r & 1) ans_right = Join(tree[--r], ans_right);
//    }
//    return Join(ans_left, ans_right).min_suf;
//  }
};

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0); 

  int n; cin >> n; cin.get();
  string s; getline(cin, s);
  int q; cin >> q;
  vector<vector<pair<int, int>>> qrs(n);
  for (int i = 0; i < q; ++i) {
    int l, r; cin >> l >> r; --l, --r;
//    dbg() name(l) name(r) endl;
    qrs[l].emplace_back(i, r);
  }
  SegmTree st(n);
  vector<int> ans(q), stk;
  for (int i = n - 1; i >= 0; --i) {
    int x = s[i] == 'C' ? +1 : -1;
    if (x == 1) {
      if (!stk.empty()) {
        st.Update(stk.back(), -1);
        stk.pop_back();
      }
      st.Update(i, x);
    }
    if (x == -1) {
      stk.emplace_back(i);
    }
//    dbg() name(i) "stk: " << endl;
//    for (auto &x : stk) dbg() x << ' '; dbg() endl;
    for (auto &p : qrs[i]) {
      int idx, r; tie(idx, r) = p;
      ans[idx] = upper_bound(stk.rbegin(), stk.rend(), r) - stk.rbegin();
//      dbg() name(idx + 1) name(ans[idx]) endl;
      ans[idx] -= st.Query(i, r);
    }
  }
  for (int i = 0; i < q; ++i) {
    cout << ans[i] << '\n';
  }
}

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