Problem p03823 (C++)

Buggy submission (status: Time Limit Exceeded):
#include "bits/stdc++.h"

#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fr(x) freopen(x, "r", stdin)
#define fw(x) freopen(x, "w", stdout)
#define iout(x) printf("%d\n", x)
#define lout(x) printf("%lld\n", x)
#define REP(x, l, u) for (ll x = (l); x <= (u); x++)
#define RREP(x, l, u) for (ll x = (l); x >= (u); x--)
#define mst(x, a) memset(x, a, sizeof(x))
#define PII pair<int, int>
#define PLL pair<ll, ll>
#define MP make_pair
#define se second
#define fi first
#define dbg(x) cout << #x << " = " << (x) << endl;
#define sz(x) ((int)x.size())
#define cl(x) x.clear()

typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ld;
using namespace std;

const int maxn = 100010;
const int mod = 1e9 + 7;
const int MAX = 1000000010;
const double eps = 1e-6;
const double PI = acos(-1);

template <typename T> inline void read(T &x) {
  x = 0;
  T f = 1;
  char ch;
  do {
    ch = getchar();
    if (ch == '-')
      f = -1;
  } while (ch < '0' || ch > '9');
  do
    x = x * 10 + ch - '0', ch = getchar();
  while (ch <= '9' && ch >= '0');
  x *= f;
}

template <typename A, typename B> inline void read(A &x, B &y) {
  read(x);
  read(y);
}
template <typename A, typename B, typename C>
inline void read(A &x, B &y, C &z) {
  read(x);
  read(y);
  read(z);
}
template <typename A, typename B, typename C, typename D>
inline void read(A &x, B &y, C &z, D &w) {
  read(x);
  read(y);
  read(z);
  read(w);
}
template <typename A, typename B> inline A fexp(A x, B p) {
  A ans = 1;
  for (; p; p >>= 1, x = 1LL * x * x % mod)
    if (p & 1)
      ans = 1LL * ans * x % mod;
  return ans;
}
template <typename A, typename B> inline A fexp(A x, B p, A mo) {
  A ans = 1;
  for (; p; p >>= 1, x = 1LL * x * x % mo)
    if (p & 1)
      ans = 1LL * ans * x % mo;
  return ans;
}

int n;

ll A, B, S[maxn];

int sm[maxn * 42], ls[maxn * 42], rs[maxn * 42], sz;

int f[maxn], g[maxn];

void update(int x, int &y, int l, int r, int t, int v) {
  if (t < 0 || t > n)
    return;
  sm[y = ++sz] = (sm[x] + v) % mod;
  ls[y] = ls[x];
  rs[y] = rs[x];
  if (l == r)
    return;
  int M = l + r >> 1;
  if (t <= M)
    update(ls[x], ls[y], l, M, t, v);
  else
    update(rs[x], rs[y], M + 1, r, t, v);
}

int query(int x, int l, int r, int L, int R) {
  if (L > R)
    return 0;
  if (!x)
    return 0;
  if (L <= l && r <= R)
    return sm[x];
  int M = l + r >> 1, ans = 0;
  if (L <= M)
    ans = query(ls[x], l, M, L, R);
  if (r > M)
    ans = (ans + query(rs[x], M + 1, r, L, R)) % mod;
  return ans;
}

void Work() {
  update(f[1], f[1], 0, n, 0, 1);
  update(g[1], g[1], 0, n, 0, 1);
  REP(i, 2, n) {
    if (S[i] - S[i - 1] >= A)
      f[i] = f[i - 1];
    if (S[i] - S[i - 1] >= B)
      g[i] = g[i - 1];
    int x;
    x = upper_bound(S + 1, S + n + 1, S[i] - A) - S - 1;
    update(f[i], f[i], 0, n, i - 1, query(g[i - 1], 0, n, 0, x));
    x = upper_bound(S + 1, S + n + 1, S[i] - B) - S - 1;
    update(g[i], g[i], 0, n, i - 1, query(f[i - 1], 0, n, 0, x));
  }
  int ans = (query(f[n], 0, n, 0, n) + query(g[n], 0, n, 0, n)) % mod;
  iout(ans);
}

void Init() {
  read(n, A, B);
  REP(i, 1, n) read(S[i]);
}

int main() {
  Init();
  Work();
  return 0;
}


Fixed submission:
#include "bits/stdc++.h"

#define PB push_back
#define PF push_front
#define LB lower_bound
#define UB upper_bound
#define fr(x) freopen(x, "r", stdin)
#define fw(x) freopen(x, "w", stdout)
#define iout(x) printf("%d\n", x)
#define lout(x) printf("%lld\n", x)
#define REP(x, l, u) for (ll x = (l); x <= (u); x++)
#define RREP(x, l, u) for (ll x = (l); x >= (u); x--)
#define mst(x, a) memset(x, a, sizeof(x))
#define PII pair<int, int>
#define PLL pair<ll, ll>
#define MP make_pair
#define se second
#define fi first
#define dbg(x) cout << #x << " = " << (x) << endl;
#define sz(x) ((int)x.size())
#define cl(x) x.clear()

typedef long long ll;
typedef unsigned long long ull;
typedef double db;
typedef long double ld;
using namespace std;

const int maxn = 100010;
const int mod = 1e9 + 7;
const int MAX = 1000000010;
const double eps = 1e-6;
const double PI = acos(-1);

template <typename T> inline void read(T &x) {
  x = 0;
  T f = 1;
  char ch;
  do {
    ch = getchar();
    if (ch == '-')
      f = -1;
  } while (ch < '0' || ch > '9');
  do
    x = x * 10 + ch - '0', ch = getchar();
  while (ch <= '9' && ch >= '0');
  x *= f;
}

template <typename A, typename B> inline void read(A &x, B &y) {
  read(x);
  read(y);
}
template <typename A, typename B, typename C>
inline void read(A &x, B &y, C &z) {
  read(x);
  read(y);
  read(z);
}
template <typename A, typename B, typename C, typename D>
inline void read(A &x, B &y, C &z, D &w) {
  read(x);
  read(y);
  read(z);
  read(w);
}
template <typename A, typename B> inline A fexp(A x, B p) {
  A ans = 1;
  for (; p; p >>= 1, x = 1LL * x * x % mod)
    if (p & 1)
      ans = 1LL * ans * x % mod;
  return ans;
}
template <typename A, typename B> inline A fexp(A x, B p, A mo) {
  A ans = 1;
  for (; p; p >>= 1, x = 1LL * x * x % mo)
    if (p & 1)
      ans = 1LL * ans * x % mo;
  return ans;
}

int n;

ll A, B, S[maxn];

int sm[maxn * 42], ls[maxn * 42], rs[maxn * 42], sz;

int f[maxn], g[maxn];

void update(int x, int &y, int l, int r, int t, int v) {
  if (t < 0 || t > n)
    return;
  sm[y = ++sz] = (sm[x] + v) % mod;
  ls[y] = ls[x];
  rs[y] = rs[x];
  if (l == r)
    return;
  int M = l + r >> 1;
  if (t <= M)
    update(ls[x], ls[y], l, M, t, v);
  else
    update(rs[x], rs[y], M + 1, r, t, v);
}

int query(int x, int l, int r, int L, int R) {
  if (L > R)
    return 0;
  if (!x)
    return 0;
  if (L <= l && r <= R)
    return sm[x];
  int M = l + r >> 1, ans = 0;
  if (L <= M)
    ans = query(ls[x], l, M, L, R);
  if (R > M)
    ans = (ans + query(rs[x], M + 1, r, L, R)) % mod;
  return ans;
}

void Work() {
  update(f[1], f[1], 0, n, 0, 1);
  update(g[1], g[1], 0, n, 0, 1);
  REP(i, 2, n) {
    if (S[i] - S[i - 1] >= A)
      f[i] = f[i - 1];
    if (S[i] - S[i - 1] >= B)
      g[i] = g[i - 1];
    int x;
    x = upper_bound(S + 1, S + n + 1, S[i] - A) - S - 1;
    update(f[i], f[i], 0, n, i - 1, query(g[i - 1], 0, n, 0, x));
    x = upper_bound(S + 1, S + n + 1, S[i] - B) - S - 1;
    update(g[i], g[i], 0, n, i - 1, query(f[i - 1], 0, n, 0, x));
  }
  int ans = (query(f[n], 0, n, 0, n) + query(g[n], 0, n, 0, n)) % mod;
  iout(ans);
}

void Init() {
  read(n, A, B);
  REP(i, 1, n) read(S[i]);
}

int main() {
  Init();
  Work();
  return 0;
}