Submission #105890

#	Time	Username	Problem	Language	Result	Execution time	Memory
105890		IOrtroiii	Election (BOI18_election)	C++14	100 / 100	990 ms	46372 KiB

election

#include <bits/stdc++.h>

using namespace std;

const int N = 500500;

int n;
char s[N];

struct Data {
  int sum, suf;
};

Data t[N << 2];

Data mrg(Data l, Data r) {
  Data ans;
  ans.sum = l.sum + r.sum;
  ans.suf = min(r.suf, r.sum + l.suf);
  return ans;
}

void upd(int v,int l,int r,int p,int x) {
  if (l == r) {
    t[v].sum = x;
    t[v].suf = min(x, 0);
    return;
  }
  int md = (l + r) >> 1;
  if (p <= md) upd(v << 1, l, md, p, x);
  else upd(v << 1 | 1, md + 1, r, p, x);
  t[v] = mrg(t[v << 1], t[v << 1 | 1]);
}

Data get(int v,int l,int r,int L,int R) {
  if (L <= l && r <= R) return t[v];
  int md = (l + r) >> 1;
  Data ans = {0, 0};
  if (L <= md) ans = mrg(ans, get(v << 1, l, md, L, R));
  if (R > md) ans = mrg(ans, get(v << 1 | 1, md + 1, r, L, R));
  return ans;
}

int ft[N];

void add(int p,int v) { for (; p <= n; p += p & -p) ft[p] += v; }
int get(int p) { int ans = 0; for (; p > 0; p -= p & -p) ans += ft[p]; return ans; }
int get(int l,int r) { return get(r) - get(l - 1); }

int ans[N];
vector< pair<int, int> > queryAt[N];

int main() {
  scanf("%d %s", &n, s + 1);
  int m;
  scanf("%d", &m);
  for (int i = 1; i <= m; ++i) {
    int l, r;
    scanf("%d %d", &l, &r);
    queryAt[l].push_back(make_pair(r, i));
  }
  vector<int> delt;
  for (int i = n; i > 0; --i) {
    if (s[i] == 'T') {
      add(i, 1);
      delt.push_back(i);
    } else {
      upd(1, 1, n, i, 1);
      if (delt.size()) {
        add(delt.back(), -1);
        upd(1, 1, n, delt.back(), -1);
        delt.pop_back();
      }
    }
    for (auto q : queryAt[i]) {
      ans[q.second] = get(i, q.first) - get(1, 1, n, i, q.first).suf;
    }
  }
  for (int i = 1; i <= m; ++i) {
    printf("%d\n", ans[i]);
  }
}

Compilation message (stderr)

election.cpp: In function 'int main()':
election.cpp:54:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %s", &n, s + 1);
   ~~~~~^~~~~~~~~~~~~~~~~~~~
election.cpp:56:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &m);
   ~~~~~^~~~~~~~~~
election.cpp:59:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &l, &r);
     ~~~~~^~~~~~~~~~~~~~~~~

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