Problem p02599 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
// ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
// clock_t start=clock();clock_t
// end=clock();cout<<(double)(end-start)/CLOCKS_PER_SEC<<endl;
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef unsigned int ui;
typedef pair<int, int> pii;
typedef pair<pii, int> ppii;
typedef pair<int, pii> pipi;
typedef pair<ll, ll> pll;
typedef pair<pll, ll> ppll;
typedef pair<ll, pll> plpl;
typedef pair<pii, pii> pippi;
typedef tuple<ll, ll, ll> tl;
typedef pair<double, double> pdd;
typedef vector<vector<ll>> mat;
ll mod = 1000000007;
ll mod2 = 998244353;
ll mod3 = 1000003;
ll mod4 = 998244853;
ll mod5 = 1000000009;
ll inf = 1LL << 61;
int iinf = 1 << 30;
double pi = 3.14159265358979323846;
double pi2 = pi / 2.0;
double eps = 1e-8;
#define rep(i, m, n) for (ll i = m; i < n; i++)
#define rrep(i, n, m) for (ll i = n; i >= m; i--)
#define srep(itr, st) for (auto itr = st.begin(); itr != st.end(); itr++)
#define mrep(itr, mp) for (auto &itr : mp)
#define Max(a, b) a = max(a, b)
#define Min(a, b) a = min(a, b)
// #define endl "\n"
int dh[4] = {1, 0, -1, 0};
int dw[4] = {0, 1, 0, -1};
int ddh[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
int ddw[8] = {-1, 0, 1, -1, 1, -1, 0, 1};
struct custom_hash {
  static uint64_t splitmix64(uint64_t x) {
    // http://xorshift.di.unimi.it/splitmix64.c
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }

  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM =
        chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};
#define umh unordered_map<int, int, custom_hash>
ll gcd(ll a, ll b) {
  if (a < 0)
    a = -a;
  if (b < 0)
    b = -b;
  if (a < b)
    swap(a, b);
  if (b == 0)
    return a;
  if (a % b == 0)
    return b;
  return gcd(b, a % b);
}
ll lcm(ll a, ll b) {
  ll c = gcd(a, b);
  return a * b / c;
}
ll Pow(ll n, ll k) {
  if (k < 0)
    return 0;
  ll ret = 1;
  ll now = n;
  while (k > 0) {
    if (k & 1)
      ret *= now;
    now *= now;
    k /= 2;
  }
  return ret;
}
ll beki(ll n, ll k, ll md) {
  ll ret = 1;
  ll now = n;
  now %= md;
  while (k > 0) {
    if (k % 2 == 1) {
      ret *= now;
      ret %= md;
    }
    now *= now;
    now %= md;
    k /= 2;
  }
  return ret;
}
ll gyaku(ll n, ll md) { return beki(n, md - 2, md); }
ll popcount(ll n) {
  ll ret = 0;
  ll u = n;
  while (u > 0) {
    ret += u % 2;
    u /= 2;
  }
  return ret;
}
struct BIT {
private:
  ll u;
  vector<ll> bit;

public:
  BIT(ll n) {
    u = 1;
    while (u < n)
      u *= 2;
    bit.resize(u + 10, 0);
  }
  void add(ll n, ll x) {
    ll i = n;
    bit[i] += x;
    // bit[i]%=mod;
    while (i < u) {
      i += i & (-i);
      bit[i] += x;
      // bit[i]%=mod;
    }
  }
  ll sum(ll n) {
    ll i = n;
    ll ret = 0;
    while (i > 0) {
      ret += bit[i];
      i -= i & (-i);
      // ret%=mod;
    }
    return ret;
  }
  ll lb(ll w) {
    if (w <= 0)
      return 0;
    ll x = 0;
    for (ll k = u; k > 0; k /= 2) {
      if (x + k <= u && bit[x + k] < w) {
        w -= bit[x + k];
        x += k;
      }
    }
    return x + 1;
  }
};
// vector<BIT> b(26,n+1);
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ll n, q;
  cin >> n >> q;
  ll c[n + 1];
  vector<ll> v[n + 1];
  rep(i, 1, n + 1) {
    cin >> c[i];
    v[c[i]].push_back(i);
  }
  ll nex[n];
  BIT b(n + 1);
  rep(i, 1, n + 1) {
    rep(j, 0, v[i].size()) {
      if (j == v[i].size() - 1)
        nex[v[i][j]] = n + 1;
      else
        nex[v[i][j]] = v[i][j + 1];
    }
    if (v[i].size() > 0)
      b.add(v[i][0], 1);
  }
  vector<pll> w[n + 1];
  rep(i, 0, q) {
    ll a, b;
    cin >> a >> b;
    w[a].push_back({b, i});
  }
  ll ans[q];
  rep(i, 1, n + 1) {
    rep(j, 0, w[i].size()) { ans[w[i][j].second] = b.sum(w[i][j].first); }
    b.add(i, -1);
    b.add(nex[i], 1);
  }
  rep(i, 0, q) cout << ans[i] << endl;
}


Fixed submission:
#include <bits/stdc++.h>
// ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
// clock_t start=clock();clock_t
// end=clock();cout<<(double)(end-start)/CLOCKS_PER_SEC<<endl;
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef unsigned int ui;
typedef pair<int, int> pii;
typedef pair<pii, int> ppii;
typedef pair<int, pii> pipi;
typedef pair<ll, ll> pll;
typedef pair<pll, ll> ppll;
typedef pair<ll, pll> plpl;
typedef pair<pii, pii> pippi;
typedef tuple<ll, ll, ll> tl;
typedef pair<double, double> pdd;
typedef vector<vector<ll>> mat;
ll mod = 1000000007;
ll mod2 = 998244353;
ll mod3 = 1000003;
ll mod4 = 998244853;
ll mod5 = 1000000009;
ll inf = 1LL << 61;
int iinf = 1 << 30;
double pi = 3.14159265358979323846;
double pi2 = pi / 2.0;
double eps = 1e-8;
#define rep(i, m, n) for (ll i = m; i < n; i++)
#define rrep(i, n, m) for (ll i = n; i >= m; i--)
#define srep(itr, st) for (auto itr = st.begin(); itr != st.end(); itr++)
#define mrep(itr, mp) for (auto &itr : mp)
#define Max(a, b) a = max(a, b)
#define Min(a, b) a = min(a, b)
// #define endl "\n"
int dh[4] = {1, 0, -1, 0};
int dw[4] = {0, 1, 0, -1};
int ddh[8] = {-1, -1, -1, 0, 0, 1, 1, 1};
int ddw[8] = {-1, 0, 1, -1, 1, -1, 0, 1};
struct custom_hash {
  static uint64_t splitmix64(uint64_t x) {
    // http://xorshift.di.unimi.it/splitmix64.c
    x += 0x9e3779b97f4a7c15;
    x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
    x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
    return x ^ (x >> 31);
  }

  size_t operator()(uint64_t x) const {
    static const uint64_t FIXED_RANDOM =
        chrono::steady_clock::now().time_since_epoch().count();
    return splitmix64(x + FIXED_RANDOM);
  }
};
#define umh unordered_map<int, int, custom_hash>
ll gcd(ll a, ll b) {
  if (a < 0)
    a = -a;
  if (b < 0)
    b = -b;
  if (a < b)
    swap(a, b);
  if (b == 0)
    return a;
  if (a % b == 0)
    return b;
  return gcd(b, a % b);
}
ll lcm(ll a, ll b) {
  ll c = gcd(a, b);
  return a * b / c;
}
ll Pow(ll n, ll k) {
  if (k < 0)
    return 0;
  ll ret = 1;
  ll now = n;
  while (k > 0) {
    if (k & 1)
      ret *= now;
    now *= now;
    k /= 2;
  }
  return ret;
}
ll beki(ll n, ll k, ll md) {
  ll ret = 1;
  ll now = n;
  now %= md;
  while (k > 0) {
    if (k % 2 == 1) {
      ret *= now;
      ret %= md;
    }
    now *= now;
    now %= md;
    k /= 2;
  }
  return ret;
}
ll gyaku(ll n, ll md) { return beki(n, md - 2, md); }
ll popcount(ll n) {
  ll ret = 0;
  ll u = n;
  while (u > 0) {
    ret += u % 2;
    u /= 2;
  }
  return ret;
}
struct BIT {
private:
  ll u;
  vector<ll> bit;

public:
  BIT(ll n) {
    u = 1;
    while (u < n)
      u *= 2;
    bit.resize(u + 10, 0);
  }
  void add(ll n, ll x) {
    ll i = n;
    bit[i] += x;
    // bit[i]%=mod;
    while (i < u) {
      i += i & (-i);
      bit[i] += x;
      // bit[i]%=mod;
    }
  }
  ll sum(ll n) {
    ll i = n;
    ll ret = 0;
    while (i > 0) {
      ret += bit[i];
      i -= i & (-i);
      // ret%=mod;
    }
    return ret;
  }
  ll lb(ll w) {
    if (w <= 0)
      return 0;
    ll x = 0;
    for (ll k = u; k > 0; k /= 2) {
      if (x + k <= u && bit[x + k] < w) {
        w -= bit[x + k];
        x += k;
      }
    }
    return x + 1;
  }
};
// vector<BIT> b(26,n+1);
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ll n, q;
  cin >> n >> q;
  ll c[n + 1];
  vector<ll> v[n + 1];
  rep(i, 1, n + 1) {
    cin >> c[i];
    v[c[i]].push_back(i);
  }
  ll nex[n + 1];
  BIT b(n + 1);
  rep(i, 1, n + 1) {
    rep(j, 0, v[i].size()) {
      if (j == v[i].size() - 1)
        nex[v[i][j]] = n + 1;
      else
        nex[v[i][j]] = v[i][j + 1];
    }
    if (v[i].size() > 0)
      b.add(v[i][0], 1);
  }
  vector<pll> w[n + 1];
  rep(i, 0, q) {
    ll a, b;
    cin >> a >> b;
    w[a].push_back({b, i});
  }
  ll ans[q];
  rep(i, 1, n + 1) {
    rep(j, 0, w[i].size()) { ans[w[i][j].second] = b.sum(w[i][j].first); }
    b.add(i, -1);
    b.add(nex[i], 1);
  }
  rep(i, 0, q) cout << ans[i] << endl;
}