Problem p03717 (C++)

Buggy submission (status: Memory Limit Exceeded):
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#define _USE_MATH_DEFINES
#include <complex>
#include <functional>
#include <math.h>
using namespace std;

#define rep(i, x) for (ll i = 0; i < x; i++)
#define repn(i, x) for (ll i = 1; i <= x; i++)

typedef long long ll;
const ll INF = 1e17;
const ll MOD = 1000000007;
const ll MAX = 4000001;
const double eps = 1E-18;

ll max(ll a, ll b) {
  if (a > b) {
    return a;
  }
  return b;
}

ll min(ll a, ll b) {
  if (a > b) {
    return b;
  }
  return a;
}

ll gcd(ll a, ll b) {
  if (b == 0) {
    return a;
  }
  if (a < b) {
    return gcd(b, a);
  }
  return gcd(b, a % b);
}

ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

struct edge {
  ll ind;
  ll fr;
  ll to;
  ll d;
};

class mint {
  long long x;

public:
  mint(long long x = 0) : x((x % MOD + MOD) % MOD) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint &a) {
    if ((x += a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator-=(const mint &a) {
    if ((x += MOD - a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator*=(const mint &a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  mint operator+(const mint &a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint &a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint &a) const {
    mint res(*this);
    return res *= a;
  }

  mint operator^(const ll &t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }
  // for prime MOD
  mint inv() const { return pow(MOD - 2); }
  mint &operator/=(const mint &a) { return (*this) *= a.inv(); }
  mint operator/(const mint &a) const {
    mint res(*this);
    return res /= a;
  }

  friend ostream &operator<<(ostream &os, const mint &m) {
    os << m.x;
    return os;
  }
};

///////////////////////////

int main() {
  ll N, M;
  cin >> N >> M;

  vector<vector<pair<ll, ll>>> cd(N + 1);
  repn(i, M) {
    ll l, r, x;
    cin >> l >> r >> x;
    cd[r].push_back({l, x});
  }

  vector<vector<vector<ll>>> dp(
      N + 1, vector<vector<ll>>(N + 1, vector<ll>(N + 1, 0)));
  vector<vector<vector<ll>>> rdp(
      N + 1, vector<vector<ll>>(N + 1, vector<ll>(N + 1, 0)));

  rep(i, N + 1) rep(j, N + 1) rep(k, N + 1) {
    if (k >= j && j >= i) {

      bool b = 1;
      for (auto p : cd[k]) {
        ll l = p.first;
        ll x = p.second;
        ll c = 1;
        if (i >= l) {
          c++;
        }
        if (j >= l) {
          c++;
        }
        if (c != x) {
          b = 0;
        }
      }

      if (b == 1) {
        if (k == 0) {
          dp[i][j][k] = 1;
        } else if (k - j == 1) {
          dp[i][j][k] = rdp[i][j][j];
        } else if (k - j > 1) {
          dp[i][j][k] = dp[i][j][k - 1];
        }
      }
    }

    else {
      ll v[3] = {i, j, k};
      sort(v, v + 3);
      dp[i][j][k] = dp[v[0]][v[1]][v[2]];
    }

    if (k == 0) {
      rdp[i][j][k] = dp[i][j][k];
    } else {
      rdp[i][j][k] = rdp[i][j][k - 1] + dp[i][j][k];
    }

    dp[i][j][k] %= MOD;
    rdp[i][j][k] %= MOD;
  }

  mint ans = 0;
  rep(i, N + 1) rep(j, N + 1) { ans += dp[i][j][N]; }
  ans *= 3;
  cout << ans << endl;

  system("PAUSE");
}


Fixed submission:
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#define _USE_MATH_DEFINES
#include <complex>
#include <functional>
#include <math.h>
using namespace std;

#define rep(i, x) for (ll i = 0; i < x; i++)
#define repn(i, x) for (ll i = 1; i <= x; i++)

typedef long long ll;
const ll INF = 1e17;
const ll MOD = 1000000007;
const ll MAX = 4000001;
const double eps = 1E-18;

ll max(ll a, ll b) {
  if (a > b) {
    return a;
  }
  return b;
}

ll min(ll a, ll b) {
  if (a > b) {
    return b;
  }
  return a;
}

ll gcd(ll a, ll b) {
  if (b == 0) {
    return a;
  }
  if (a < b) {
    return gcd(b, a);
  }
  return gcd(b, a % b);
}

ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

struct edge {
  ll ind;
  ll fr;
  ll to;
  ll d;
};

class mint {
  long long x;

public:
  mint(long long x = 0) : x((x % MOD + MOD) % MOD) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint &a) {
    if ((x += a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator-=(const mint &a) {
    if ((x += MOD - a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator*=(const mint &a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  mint operator+(const mint &a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint &a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint &a) const {
    mint res(*this);
    return res *= a;
  }

  mint operator^(const ll &t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }
  // for prime MOD
  mint inv() const { return pow(MOD - 2); }
  mint &operator/=(const mint &a) { return (*this) *= a.inv(); }
  mint operator/(const mint &a) const {
    mint res(*this);
    return res /= a;
  }

  friend ostream &operator<<(ostream &os, const mint &m) {
    os << m.x;
    return os;
  }
};

///////////////////////////

int main() {
  ll N, M;
  cin >> N >> M;

  vector<vector<pair<ll, ll>>> cd(N + 1);
  repn(i, M) {
    ll l, r, x;
    cin >> l >> r >> x;
    cd[r].push_back({l, x});
  }

  vector<vector<vector<int>>> dp(
      N + 1, vector<vector<int>>(N + 1, vector<int>(N + 1, 0)));
  vector<vector<vector<int>>> rdp(
      N + 1, vector<vector<int>>(N + 1, vector<int>(N + 1, 0)));

  rep(i, N + 1) rep(j, N + 1) rep(k, N + 1) {
    if (k >= j && j >= i) {

      bool b = 1;
      for (auto p : cd[k]) {
        ll l = p.first;
        ll x = p.second;
        ll c = 1;
        if (i >= l) {
          c++;
        }
        if (j >= l) {
          c++;
        }
        if (c != x) {
          b = 0;
        }
      }

      if (b == 1) {
        if (k == 0) {
          dp[i][j][k] = 1;
        } else if (k - j == 1) {
          dp[i][j][k] = rdp[i][j][j];
        } else if (k - j > 1) {
          dp[i][j][k] = dp[i][j][k - 1];
        }
      }
    }

    else {
      ll v[3] = {i, j, k};
      sort(v, v + 3);
      dp[i][j][k] = dp[v[0]][v[1]][v[2]];
    }

    if (k == 0) {
      rdp[i][j][k] = dp[i][j][k];
    } else {
      rdp[i][j][k] = rdp[i][j][k - 1] + dp[i][j][k];
    }

    dp[i][j][k] %= MOD;
    rdp[i][j][k] %= MOD;
  }

  mint ans = 0;
  rep(i, N + 1) rep(j, N + 1) { ans += dp[i][j][N]; }
  ans *= 3;
  cout << ans << endl;

  system("PAUSE");
}