Problem p01434 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;
using namespace placeholders;

typedef long long LL;
typedef unsigned long long ULL;
typedef vector<int> VI;
typedef vector<vector<int>> VVI;
typedef vector<string> VS;
typedef stringstream SS;
typedef pair<int, int> PII;
typedef vector<pair<int, int>> VPII;
#define VT(T) vector<T>
#define VVT(T) vector<vector<T>>
#define LIM(T) numeric_limits<T>

template <typename T> inline istream &operator>>(istream &s, vector<T> &v) {
  for (T &t : v) {
    s >> t;
  }
  return s;
}
template <typename T>
inline ostream &operator<<(ostream &s, const vector<T> &v) {
  for (int i = 0; i < int(v.size()); ++i) {
    s << (" " + !i) << v[i];
  }
  return s;
}
template <typename T> inline T fromString(const string &s) {
  T res;
  istringstream iss(s);
  iss >> res;
  return res;
};
template <typename T> inline string toString(const T &a) {
  ostringstream oss;
  oss << a;
  return oss.str();
};

#define REP2(i, n) REP3(i, 0, n)
#define REP3(i, m, n) for (int i = (int)(m); i < (int)(n); ++i)
#define GET_REP(a, b, c, F, ...) F
#define REP(...) GET_REP(__VA_ARGS__, REP3, REP2)(__VA_ARGS__)
#define FOR(e, c) for (auto &e : c)
#define ALL(c) (c).begin(), (c).end()
#define AALL(a, t) (t *)a, (t *)a + sizeof(a) / sizeof(t)
#define DRANGE(c, p) (c).begin(), (c).begin() + p, (c).end()

#define SZ(v) ((int)(v).size())
#define PB push_back
#define EM emplace
#define EB emplace_back
#define BI back_inserter

#define EXIST(c, e) ((c).find(e) != (c).end())

#define MP make_pair
#define fst first
#define snd second

#define DUMP(x) cerr << #x << " = " << (x) << endl

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  for (int N, M; cin >> N >> M && (N | M);) {
    VI S(N), T(S);
    REP(i, N) { cin >> S[i] >> T[i]; }

    VI P(M);
    cin >> P;
    P.PB(1000000001);
    sort(ALL(P));

    VI evens(M), odds(M);
    REP(i, M) { (i % 2 ? odds : evens)[i] = P[i + 1] - P[i]; }

    VI csum_even(1, 0), csum_odd(1, 0);
    partial_sum(ALL(evens), BI(csum_even));
    partial_sum(ALL(odds), BI(csum_odd));

    LL res = 0;
    REP(i, N) {
      int s, t;
      tie(s, t) = minmax(S[i], T[i]);

      const int p = lower_bound(ALL(P), s) - P.begin();
      const int q = upper_bound(ALL(P), t) - P.begin();

      VI &ary = p % 2 ? csum_odd : csum_even;

      int tmp = (t - s) - (ary[q] - ary[p]);
      if ((q - p) % 2) {
        tmp += P[q] - t;
      }
      if ((q - p) % 2 && S[i] > T[i]) {
        tmp = (t - s) - tmp;
      }
      res += tmp;
    }
    cout << res << endl;
  }

  return 0;
}

Error: TLE

Fixed submission:

#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <deque>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;
using namespace placeholders;

typedef long long LL;
typedef unsigned long long ULL;
typedef vector<int> VI;
typedef vector<vector<int>> VVI;
typedef vector<string> VS;
typedef stringstream SS;
typedef pair<int, int> PII;
typedef vector<pair<int, int>> VPII;
#define VT(T) vector<T>
#define VVT(T) vector<vector<T>>
#define LIM(T) numeric_limits<T>

template <typename T> inline istream &operator>>(istream &s, vector<T> &v) {
  for (T &t : v) {
    s >> t;
  }
  return s;
}
template <typename T>
inline ostream &operator<<(ostream &s, const vector<T> &v) {
  for (int i = 0; i < int(v.size()); ++i) {
    s << (" " + !i) << v[i];
  }
  return s;
}
template <typename T> inline T fromString(const string &s) {
  T res;
  istringstream iss(s);
  iss >> res;
  return res;
};
template <typename T> inline string toString(const T &a) {
  ostringstream oss;
  oss << a;
  return oss.str();
};

#define REP2(i, n) REP3(i, 0, n)
#define REP3(i, m, n) for (int i = (int)(m); i < (int)(n); ++i)
#define GET_REP(a, b, c, F, ...) F
#define REP(...) GET_REP(__VA_ARGS__, REP3, REP2)(__VA_ARGS__)
#define FOR(e, c) for (auto &e : c)
#define ALL(c) (c).begin(), (c).end()
#define AALL(a, t) (t *)a, (t *)a + sizeof(a) / sizeof(t)
#define DRANGE(c, p) (c).begin(), (c).begin() + p, (c).end()

#define SZ(v) ((int)(v).size())
#define PB push_back
#define EM emplace
#define EB emplace_back
#define BI back_inserter

#define EXIST(c, e) ((c).find(e) != (c).end())

#define MP make_pair
#define fst first
#define snd second

#define DUMP(x) cerr << #x << " = " << (x) << endl

LL cut(const int S, const int T, const VI &P) {
  int s, t;
  tie(s, t) = minmax(S, T);

  VI ps({s, t});
  FOR(p, P) {
    if (s < p && p < t) {
      ps.PB(p);
    }
  }

  const int N = SZ(ps);
  sort(ALL(ps));

  LL res = 0;
  for (int i = 0; i + 1 < N; i += 2) {
    res += ps[i + 1] - ps[i];
  }
  return N % 2 && S > T ? (t - s) - res : res;
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  for (int N, M; cin >> N >> M && (N | M);) {
    VI S(N), T(S);
    REP(i, N) { cin >> S[i] >> T[i]; }

    VI P(M);
    cin >> P;

    LL res = 0;
    REP(i, N) { res += cut(S[i], T[i], P); }
    cout << res << endl;
  }

  return 0;
}