Problem p02549 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <bits/stdc++.h>
using namespace std;
void __print(int x) { cout << x; }
void __print(long x) { cout << x; }
void __print(long long x) { cout << x; }
void __print(unsigned x) { cout << x; }
void __print(unsigned long x) { cout << x; }
void __print(unsigned long long x) { cout << x; }
void __print(float x) { cout << x; }
void __print(double x) { cout << x; }
void __print(long double x) { cout << x; }
void __print(char x) { cout << '\\'' << x << '\\''; }
void __print(const char *x) { cout << '\\"' << x << '\\"'; }
void __print(const string &x) { cout << '\\"' << x << '\\"'; }
void __print(bool x) { cout << (x ? "true" : "false"); }
template <typename T, typename V> void __print(const pair<T, V> &x) {
  cout << '{';
  __print(x.first);
  cout << ',';
  __print(x.second);
  cout << '}';
}
template <typename T> void __print(const T &x) {
  int f = 0;
  cout << '{';
  for (auto &i : x)
    cout << (f++ ? "," : ""), __print(i);
  cout << "}";
}
void _print() { cout << "\\n"; }
template <typename T, typename... V> void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v))
    cout << ", ";
  _print(v...);
}
#define debug(x...)                                                            \\
  cout << #x << " = ";                                                         \\
  _print(x)
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
#define rep(i, a, b) for (int i = (a); i < (b); ++i)
#define per(i, a, b) for (int i = (b)-1; i >= (a); --i)
#define all(x) begin(x), end(x)
#define mp make_pair
#define pb push_back
#define ff first
#define ss second
#define fast                                                                   \\
  ios_base::sync_with_stdio(NULL);                                             \\
  cin.tie(NULL);                                                               \\
  cout.tie(NULL)
const int mod = 998244353, mxn = 1e5 + 1;

struct fenwick {
  int n;
  vi dat;
  void init(int x) {
    n = x;
    dat.resize(n + 1, 0);
  }
  void update(int ind, int val) {
    ind++;
    while (ind <= n) {
      dat[ind] += val;
      dat[ind] %= mod;
      ind += ind & (-ind);
    }
  }
  int sum(int ind) {
    int sum = 0;
    ind++;
    while (ind > 0) {
      sum += dat[ind];
      sum %= mod;
      ind -= ind & (-ind);
    }
    return sum;
  }
};

int solve() {
  struct fenwick bit;
  bit.init(1e6 + 77);
  int n, k;
  cin >> n >> k;
  vi l(k), r(k);
  rep(i, 0, k) cin >> l[i] >> r[i];
  vi dp(n + 1, 0);
  dp[1] = 1;
  bit.update(1, 1);
  rep(i, 2, n + 1) {
    rep(j, 0, k) {
      if (l[j] >= i)
        continue;
      int a = l[j], b = r[j];
      b = min(i - 1, b);
      a = min(i + 1, a);
      if (a > b)
        continue;
      int add = (bit.sum(i - a) - bit.sum(i - b - 1) + mod) % mod;
      dp[i] += add;
      dp[i] %= mod;
      bit.update(i, add);
    }
  }
  cout << dp[n] << "\\n";
  return 0;
}
// Counting problems: Sometimes easier to find complement of the answer

int main() {
  fast;
  int t = 1;
  // cin>> t;
  while (t--) {
    solve();
  }
  return 0;
}
// v.clear(), vis.clear(); vis.resize(n + 1, 0), v.resize(n + 1);

/*  inv[1] = 1; // inv is ll
    for(int i=2; i<=mxn; ++i)
        inv[i]=mod-mod/i*inv[mod%i]%mod;*/

// lower bound   >=
// upper bound   >
// vector<int>().swap(vec); //free memory from vec


Error: TLE

Fixed submission:

#include <bits/stdc++.h>
using namespace std;
void __print(int x) { cout << x; }
void __print(long x) { cout << x; }
void __print(long long x) { cout << x; }
void __print(unsigned x) { cout << x; }
void __print(unsigned long x) { cout << x; }
void __print(unsigned long long x) { cout << x; }
void __print(float x) { cout << x; }
void __print(double x) { cout << x; }
void __print(long double x) { cout << x; }
void __print(char x) { cout << '\\'' << x << '\\''; }
void __print(const char *x) { cout << '\\"' << x << '\\"'; }
void __print(const string &x) { cout << '\\"' << x << '\\"'; }
void __print(bool x) { cout << (x ? "true" : "false"); }
template <typename T, typename V> void __print(const pair<T, V> &x) {
  cout << '{';
  __print(x.first);
  cout << ',';
  __print(x.second);
  cout << '}';
}
template <typename T> void __print(const T &x) {
  int f = 0;
  cout << '{';
  for (auto &i : x)
    cout << (f++ ? "," : ""), __print(i);
  cout << "}";
}
void _print() { cout << "\\n"; }
template <typename T, typename... V> void _print(T t, V... v) {
  __print(t);
  if (sizeof...(v))
    cout << ", ";
  _print(v...);
}
#define debug(x...)                                                            \\
  cout << #x << " = ";                                                         \\
  _print(x)
typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vll;
#define rep(i, a, b) for (ll i = (a); i < (b); ++i)
#define per(i, a, b) for (int i = (b)-1; i >= (a); --i)
#define all(x) begin(x), end(x)
#define mp make_pair
#define pb push_back
#define ff first
#define ss second
#define fast                                                                   \\
  ios_base::sync_with_stdio(NULL);                                             \\
  cin.tie(NULL);                                                               \\
  cout.tie(NULL)
const int mod = 998244353, mxn = 1e5 + 1;

int solve() {
  int n, k;
  cin >> n >> k;
  vi gg;
  rep(i, 0, k) {
    int l, r;
    cin >> l >> r;
    rep(j, l, r + 1) gg.pb(j);
  }
  vi dp(n + 1, 0);
  dp[1] = 1;
  rep(i, 2, n + 1) {
    rep(j, 0, gg.size()) {
      if ((i - gg[j]) <= 0)
        continue;
      dp[i] += dp[i - gg[j]];
      dp[i] %= mod;
    }
  }
  cout << dp[n] << "\\n";
  return 0;
}
// Counting problems: Sometimes easier to find complement of the answer

int main() {
  fast;
  int t = 1;
  // cin>> t;
  while (t--) {
    solve();
  }
  return 0;
}
// v.clear(), vis.clear(); vis.resize(n + 1, 0), v.resize(n + 1);

/*  inv[1] = 1; // inv is ll
    for(int i=2; i<=mxn; ++i)
        inv[i]=mod-mod/i*inv[mod%i]%mod;*/

// lower bound   >=
// upper bound   >
// vector<int>().swap(vec); //free memory from vec