Problem p02599 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> ii;
typedef unsigned long long ull;

#define X first
#define Y second
#define pb push_back
#define mp make_pair
#define ep emplace_back
#define EL printf("\\n")
#define sz(A) (int)A.size()
#define FOR(i, l, r) for (int i = l; i <= r; i++)
#define FOD(i, r, l) for (int i = r; i >= l; i--)
#define fillchar(a, x) memset(a, x, sizeof(a))
#define faster                                                                 \\
  ios_base::sync_with_stdio(false);                                            \\
  cin.tie(NULL);                                                               \\
  cout.tie(NULL);

struct two {
  int i, j, type, id;
};

const int N = 500001, Q = 500001, A = 1000001;
int n, q, res[Q], last_pos[A], bit[N];
two a[N + Q];

bool cmp(two u, two v) {
  return (u.j < v.j or (u.j == v.j and u.type < v.type));
}

void update(int x, int k) {
  for (x; x <= n; x += x & -x)
    bit[x] += k;
}

int get(int x) {
  int ans = 0;
  for (x; x > 0; x -= x & -x)
    ans += bit[x];
  return ans;
}

int main() {

  scanf("%d%d", &n, &q);
  for (int i = 1; i <= n; i++)
    scanf("%d", &a[i].i), a[i].j = i, a[i].type = -1;
  for (int i = 1; i <= q; i++)
    scanf("%d%d", &a[i + n].i, &a[i + n].j), a[i + n].id = i;

  sort(a + 1, a + n + q + 1, cmp);

  for (int i = 1; i <= n + q; i++) {
    if (a[i].type == -1) {
      update(a[i].j, 1);
      if (last_pos[a[i].i] > 0)
        update(last_pos[a[i].i], -1);
      last_pos[a[i].i] = a[i].j;
    } else {
      res[a[i].id] = get(a[i].j) - get(a[i].i - 1);
    }
  }

  for (int i = 1; i <= q; i++)
    printf("%d\\n", res[i]);

  return 0;
}


Error: WA

Fixed submission:

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> ii;
typedef unsigned long long ull;

#define X first
#define Y second
#define pb push_back
#define mp make_pair
#define ep emplace_back
#define EL printf("\\n")
#define sz(A) (int)A.size()
#define FOR(i, l, r) for (int i = l; i <= r; i++)
#define FOD(i, r, l) for (int i = r; i >= l; i--)
#define fillchar(a, x) memset(a, x, sizeof(a))
#define faster                                                                 \\
  ios_base::sync_with_stdio(false);                                            \\
  cin.tie(NULL);                                                               \\
  cout.tie(NULL);

struct two {
  int i, j, type, id;
};

const int N = 30001, Q = 200001, A = 1000001;
int n, q, res[Q], last_pos[A], bit[N];
two a[N + Q];

bool cmp(two u, two v) {
  return (u.j < v.j or (u.j == v.j and u.type < v.type));
}

void update(int x, int k) {
  for (x; x <= n; x += x & -x)
    bit[x] += k;
}

int get(int x) {
  int ans = 0;
  for (x; x > 0; x -= x & -x)
    ans += bit[x];
  return ans;
}

int main() {

  scanf("%d", &n);
  for (int i = 1; i <= n; i++)
    scanf("%d", &a[i].i), a[i].j = i, a[i].type = -1;
  scanf("%d", &q);
  for (int i = 1; i <= q; i++)
    scanf("%d%d", &a[i + n].i, &a[i + n].j), a[i + n].id = i;

  sort(a + 1, a + n + q + 1, cmp);

  for (int i = 1; i <= n + q; i++) {
    if (a[i].type == -1) {
      update(a[i].j, 1);
      if (last_pos[a[i].i] > 0)
        update(last_pos[a[i].i], -1);
      last_pos[a[i].i] = a[i].j;
    } else {
      res[a[i].id] = get(a[i].j) - get(a[i].i - 1);
    }
  }

  for (int i = 1; i <= q; i++)
    printf("%d\\n", res[i]);

  return 0;
}