Problem p01414 (C++) — buggy submission, verdict: Time Limit Exceeded

#include <algorithm>
#include <bits/stdc++.h>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <string>
#include <vector>
//    #include <boost/multiprecision/cpp_int.hpp>
#include <functional>
//    #define int long long
#define inf 1000000007
#define pa pair<int, int>
#define ll long long
#define pal pair<double, pa>
#define ppap pair<pa, int>

#define ssa pair<string, int>
#define mp make_pair
#define pb push_back
#define EPS (1e-10)
#define equals(a, b) (fabs((a) - (b)) < EPS)
int dx[4] = {0, -1, 0, 1};
int dy[4] = {1, 0, -1, 0};
using namespace std;
class pa3 {
public:
  int x, y, z;
  pa3(int x = 0, int y = 0, int z = 0) : x(x), y(y), z(z) {}
  bool operator<(const pa3 &p) const {
    if (x != p.x)
      return x < p.x;
    if (y != p.y)
      return y < p.y;
    return z < p.z;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator>(const pa3 &p) const {
    if (x != p.x)
      return x > p.x;
    if (y != p.y)
      return y > p.y;
    return z > p.z;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator==(const pa3 &p) const {
    return x == p.x && y == p.y && z == p.z;
  }
  bool operator!=(const pa3 &p) const {
    return !(x == p.x && y == p.y && z == p.z);
  }
};

class pa4 {
public:
  double x;
  int y, z, w;
  pa4(double x = 0, int y = 0, int z = 0, int w = 0) : x(x), y(y), z(z), w(w) {}
  bool operator<(const pa4 &p) const {
    if (x != p.x)
      return x < p.x;
    if (y != p.y)
      return y < p.y;
    if (z != p.z)
      return z < p.z;
    return w < p.w;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator>(const pa4 &p) const {
    if (x != p.x)
      return x > p.x;
    if (y != p.y)
      return y > p.y;
    if (z != p.z)
      return z > p.z;
    return w > p.w;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator==(const pa4 &p) const {
    return x == p.x && y == p.y && z == p.z && w == p.w;
  }
};
class pa2 {
public:
  int x, y;
  pa2(int x = 0, int y = 0) : x(x), y(y) {}
  pa2 operator+(pa2 p) { return pa2(x + p.x, y + p.y); }
  pa2 operator-(pa2 p) { return pa2(x - p.x, y - p.y); }
  bool operator<(const pa2 &p) const { return x != p.x ? x < p.x : y < p.y; }
  bool operator==(const pa2 &p) const {
    return abs(x - p.x) == 0 && abs(y - p.y) == 0;
  }
  bool operator!=(const pa2 &p) const {
    return !(abs(x - p.x) == 0 && abs(y - p.y) == 0);
  }
};

#define ppa pair<int, pas>
class Point {
public:
  double x, y;
  Point(double x = 0, double y = 0) : x(x), y(y) {}
  Point operator+(Point p) { return Point(x + p.x, y + p.y); }
  Point operator-(Point p) { return Point(x - p.x, y - p.y); }
  Point operator*(double a) { return Point(x * a, y * a); }
  Point operator/(double a) { return Point(x / a, y / a); }
  double absv() { return sqrt(norm()); }
  double norm() { return x * x + y * y; }
  bool operator<(const Point &p) const { return x != p.x ? x < p.x : y < p.y; }
  bool operator==(const Point &p) const {
    return fabs(x - p.x) < EPS && fabs(y - p.y) < EPS;
  }
};
typedef Point Vector;
#define pl pair<int, pas>
struct Segment {
  Point p1, p2;
};
double dot(Vector a, Vector b) { return a.x * b.x + a.y * b.y; }
double cross(Vector a, Vector b) { return a.x * b.y - a.y * b.x; }

bool parareru(Point a, Point b, Point c, Point d) {
  //	if(abs(cross(a-b,d-c))<EPS)cout<<"dd "<<cross(a-b,d-c)<<endl;
  return abs(cross(a - b, d - c)) < EPS;
}
double distance_ls_p(Point a, Point b, Point c) {
  if (dot(b - a, c - a) < EPS)
    return (c - a).absv();
  if (dot(a - b, c - b) < EPS)
    return (c - b).absv();
  return abs(cross(b - a, c - a)) / (b - a).absv();
}
bool is_intersected_ls(Segment a, Segment b) {
  if (a.p1 == b.p1 || a.p2 == b.p1 || a.p1 == b.p2 || a.p2 == b.p2)
    return false;
  if (parareru((a.p2), (a.p1), (a.p1), (b.p2)) &&
      parareru((a.p2), (a.p1), (a.p1), (b.p1))) {
    //		cout<<"sss"<<endl;
    if (dot(a.p1 - b.p1, a.p1 - b.p2) < EPS)
      return true;
    if (dot(a.p2 - b.p1, a.p2 - b.p2) < EPS)
      return true;
    if (dot(a.p1 - b.p1, a.p2 - b.p1) < EPS)
      return true;
    if (dot(a.p1 - b.p2, a.p2 - b.p2) < EPS)
      return true;
    return false;
  } else
    return (cross(a.p2 - a.p1, b.p1 - a.p1) * cross(a.p2 - a.p1, b.p2 - a.p1) <
            EPS) &&
           (cross(b.p2 - b.p1, a.p1 - b.p1) * cross(b.p2 - b.p1, a.p2 - b.p1) <
            EPS);
}

double segment_dis(Segment a, Segment b) {
  if (is_intersected_ls(a, b))
    return 0;
  double r = distance_ls_p(a.p1, a.p2, b.p1);
  r = min(r, distance_ls_p(a.p1, a.p2, b.p2));
  r = min(r, distance_ls_p(b.p1, b.p2, a.p2));
  r = min(r, distance_ls_p(b.p1, b.p2, a.p1));
  return r;
}
Point intersection_ls(Segment a, Segment b) {
  Point ba = b.p2 - b.p1;
  double d1 = abs(cross(ba, a.p1 - b.p1));
  double d2 = abs(cross(ba, a.p2 - b.p1));
  double t = d1 / (d1 + d2);

  return a.p1 + (a.p2 - a.p1) * t;
}

string itos(int i) {
  ostringstream s;
  s << i;
  return s.str();
}

int gcd(int v, int b) {
  if (v > b)
    return gcd(b, v);
  if (v == b)
    return b;
  if (b % v == 0)
    return v;
  return gcd(v, b % v);
}

double distans(double x1, double y1, double x2, double y2) {
  double rr = (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
  return sqrt(rr);
}

//         int pr[2000010];
//       int inv[2000010];

int beki(int wa, int rr, int warukazu) {
  if (rr == 0)
    return 1ll;
  if (rr == 1)
    return wa % warukazu;
  if (rr % 2 == 1)
    return (beki(wa, rr - 1, warukazu) * wa) % warukazu;
  int zx = beki(wa, rr / 2, warukazu);
  return (zx * zx) % warukazu;
}
/*
            int comb(int nn,int rr){
                    int r=pr[nn]*inv[rr];
                    r%=inf;
                    r*=inv[nn-rr];
                    r%=inf;
                    return r;
            }

void gya(int ert){
    pr[0]=1;
    for(int i=1;i<ert;i++){
            pr[i]=(pr[i-1]*i)%inf;
    }
    for(int i=0;i<ert;i++) inv[i]=beki(pr[i],inf-2,inf);

}
 */
// priority_queue<pa3,vector<pa3>,greater<pa3>> pq;
// sort(ve.begin(),ve.end(),greater<int>());
//----------------kokomade tenpure------------
// vector<double> ans(100000000),ans2(100000000);

int n;
string s[4];
int h[20], w[20];
int dp[1 << 16];

queue<pa> pq;
vector<pa> ve;
signed main() {
  cin >> n;
  for (int i = 0; i < n; i++)
    cin >> h[i] >> w[i];
  for (int i = 0; i < (1 << 16); i++)
    dp[i] = -1;
  for (int i = 0; i < 4; i++)
    cin >> s[i];
  string ss = "RBG";

  for (int k = 0; k < n; k++) {
    for (auto c : ss)
      for (int i = 1 - h[k]; i < 4; i++)
        for (int j = 1 - w[k]; j < 4; j++) {
          int bit1 = 0, bit2 = 0;
          for (int x = max(i, 0); x < min(i + h[k], 4); x++)
            for (int y = max(j, 0); y < min(j + w[k], 4); y++) {
              bit1 += (1 << ((y)*4 + x));
              if (s[x][y] == c)
                bit2 += (1 << ((y)*4 + x));
            }
          ve.pb(mp(bit1, bit2));
        }
  }

  pq.push(mp(0, 0));
  while (pq.size() > 0) {
    pa z = pq.front();
    pq.pop();
    if (dp[z.second] >= 0)
      continue;
    dp[z.second] = z.first;
    if (z.second + 1 == (1 << 16)) {
      cout << z.first << endl;
      return 0;
    }
    //		cout<<bitset<16>(z.second)<<" "<<z.first <<endl;
    for (auto v : ve) {
      int bit = (1 << 16) - 1;
      bit ^= v.first;
      bit = bit & z.second;

      bit = bit + v.second;
      if (dp[bit] < 0)
        pq.push(mp(z.first + 1, bit));
    }
  }

  cout << dp[(1 << 16) - 1] << endl;

  return 0;
}


Error: TLE

Fixed submission:

#include <algorithm>
#include <bits/stdc++.h>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <string>
#include <vector>
//    #include <boost/multiprecision/cpp_int.hpp>
#include <functional>
//    #define int long long
#define inf 1000000007
#define pa pair<int, int>
#define ll long long
#define pal pair<double, pa>
#define ppap pair<pa, int>

#define ssa pair<string, int>
#define mp make_pair
#define pb push_back
#define EPS (1e-10)
#define equals(a, b) (fabs((a) - (b)) < EPS)
int dx[4] = {0, -1, 0, 1};
int dy[4] = {1, 0, -1, 0};
using namespace std;
class pa3 {
public:
  int x, y, z;
  pa3(int x = 0, int y = 0, int z = 0) : x(x), y(y), z(z) {}
  bool operator<(const pa3 &p) const {
    if (x != p.x)
      return x < p.x;
    if (y != p.y)
      return y < p.y;
    return z < p.z;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator>(const pa3 &p) const {
    if (x != p.x)
      return x > p.x;
    if (y != p.y)
      return y > p.y;
    return z > p.z;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator==(const pa3 &p) const {
    return x == p.x && y == p.y && z == p.z;
  }
  bool operator!=(const pa3 &p) const {
    return !(x == p.x && y == p.y && z == p.z);
  }
};

class pa4 {
public:
  double x;
  int y, z, w;
  pa4(double x = 0, int y = 0, int z = 0, int w = 0) : x(x), y(y), z(z), w(w) {}
  bool operator<(const pa4 &p) const {
    if (x != p.x)
      return x < p.x;
    if (y != p.y)
      return y < p.y;
    if (z != p.z)
      return z < p.z;
    return w < p.w;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator>(const pa4 &p) const {
    if (x != p.x)
      return x > p.x;
    if (y != p.y)
      return y > p.y;
    if (z != p.z)
      return z > p.z;
    return w > p.w;
    // return x != p.x ? x<p.x: y<p.y;
  }
  bool operator==(const pa4 &p) const {
    return x == p.x && y == p.y && z == p.z && w == p.w;
  }
};
class pa2 {
public:
  int x, y;
  pa2(int x = 0, int y = 0) : x(x), y(y) {}
  pa2 operator+(pa2 p) { return pa2(x + p.x, y + p.y); }
  pa2 operator-(pa2 p) { return pa2(x - p.x, y - p.y); }
  bool operator<(const pa2 &p) const { return x != p.x ? x < p.x : y < p.y; }
  bool operator==(const pa2 &p) const {
    return abs(x - p.x) == 0 && abs(y - p.y) == 0;
  }
  bool operator!=(const pa2 &p) const {
    return !(abs(x - p.x) == 0 && abs(y - p.y) == 0);
  }
};

#define ppa pair<int, pas>
class Point {
public:
  double x, y;
  Point(double x = 0, double y = 0) : x(x), y(y) {}
  Point operator+(Point p) { return Point(x + p.x, y + p.y); }
  Point operator-(Point p) { return Point(x - p.x, y - p.y); }
  Point operator*(double a) { return Point(x * a, y * a); }
  Point operator/(double a) { return Point(x / a, y / a); }
  double absv() { return sqrt(norm()); }
  double norm() { return x * x + y * y; }
  bool operator<(const Point &p) const { return x != p.x ? x < p.x : y < p.y; }
  bool operator==(const Point &p) const {
    return fabs(x - p.x) < EPS && fabs(y - p.y) < EPS;
  }
};
typedef Point Vector;
#define pl pair<int, pas>
struct Segment {
  Point p1, p2;
};
double dot(Vector a, Vector b) { return a.x * b.x + a.y * b.y; }
double cross(Vector a, Vector b) { return a.x * b.y - a.y * b.x; }

bool parareru(Point a, Point b, Point c, Point d) {
  //	if(abs(cross(a-b,d-c))<EPS)cout<<"dd "<<cross(a-b,d-c)<<endl;
  return abs(cross(a - b, d - c)) < EPS;
}
double distance_ls_p(Point a, Point b, Point c) {
  if (dot(b - a, c - a) < EPS)
    return (c - a).absv();
  if (dot(a - b, c - b) < EPS)
    return (c - b).absv();
  return abs(cross(b - a, c - a)) / (b - a).absv();
}
bool is_intersected_ls(Segment a, Segment b) {
  if (a.p1 == b.p1 || a.p2 == b.p1 || a.p1 == b.p2 || a.p2 == b.p2)
    return false;
  if (parareru((a.p2), (a.p1), (a.p1), (b.p2)) &&
      parareru((a.p2), (a.p1), (a.p1), (b.p1))) {
    //		cout<<"sss"<<endl;
    if (dot(a.p1 - b.p1, a.p1 - b.p2) < EPS)
      return true;
    if (dot(a.p2 - b.p1, a.p2 - b.p2) < EPS)
      return true;
    if (dot(a.p1 - b.p1, a.p2 - b.p1) < EPS)
      return true;
    if (dot(a.p1 - b.p2, a.p2 - b.p2) < EPS)
      return true;
    return false;
  } else
    return (cross(a.p2 - a.p1, b.p1 - a.p1) * cross(a.p2 - a.p1, b.p2 - a.p1) <
            EPS) &&
           (cross(b.p2 - b.p1, a.p1 - b.p1) * cross(b.p2 - b.p1, a.p2 - b.p1) <
            EPS);
}

double segment_dis(Segment a, Segment b) {
  if (is_intersected_ls(a, b))
    return 0;
  double r = distance_ls_p(a.p1, a.p2, b.p1);
  r = min(r, distance_ls_p(a.p1, a.p2, b.p2));
  r = min(r, distance_ls_p(b.p1, b.p2, a.p2));
  r = min(r, distance_ls_p(b.p1, b.p2, a.p1));
  return r;
}
Point intersection_ls(Segment a, Segment b) {
  Point ba = b.p2 - b.p1;
  double d1 = abs(cross(ba, a.p1 - b.p1));
  double d2 = abs(cross(ba, a.p2 - b.p1));
  double t = d1 / (d1 + d2);

  return a.p1 + (a.p2 - a.p1) * t;
}

string itos(int i) {
  ostringstream s;
  s << i;
  return s.str();
}

int gcd(int v, int b) {
  if (v > b)
    return gcd(b, v);
  if (v == b)
    return b;
  if (b % v == 0)
    return v;
  return gcd(v, b % v);
}

double distans(double x1, double y1, double x2, double y2) {
  double rr = (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
  return sqrt(rr);
}

//         int pr[2000010];
//       int inv[2000010];

int beki(int wa, int rr, int warukazu) {
  if (rr == 0)
    return 1ll;
  if (rr == 1)
    return wa % warukazu;
  if (rr % 2 == 1)
    return (beki(wa, rr - 1, warukazu) * wa) % warukazu;
  int zx = beki(wa, rr / 2, warukazu);
  return (zx * zx) % warukazu;
}
/*
            int comb(int nn,int rr){
                    int r=pr[nn]*inv[rr];
                    r%=inf;
                    r*=inv[nn-rr];
                    r%=inf;
                    return r;
            }

void gya(int ert){
    pr[0]=1;
    for(int i=1;i<ert;i++){
            pr[i]=(pr[i-1]*i)%inf;
    }
    for(int i=0;i<ert;i++) inv[i]=beki(pr[i],inf-2,inf);

}
 */
// priority_queue<pa3,vector<pa3>,greater<pa3>> pq;
// sort(ve.begin(),ve.end(),greater<int>());
//----------------kokomade tenpure------------
// vector<double> ans(100000000),ans2(100000000);

int n;
string s[4];
int h[20], w[20];
int dp[1 << 16];

priority_queue<pa, vector<pa>, greater<pa>> pq;

signed main() {
  cin >> n;
  for (int i = 0; i < n; i++)
    cin >> h[i] >> w[i];
  for (int i = 0; i < (1 << 16); i++)
    dp[i] = -1;
  for (int i = 0; i < 4; i++)
    cin >> s[i];
  string ss = "RBG";

  pq.push(mp(0, 0));
  while (pq.size() > 0) {
    pa z = pq.top();
    pq.pop();
    if (dp[z.second] >= 0)
      continue;
    dp[z.second] = z.first;
    if (z.second + 1 == (1 << 16)) {
      cout << z.first << endl;
      return 0;
    }
    //	if(z.first==1)	cout<<bitset<16>(z.second)<<" "<<z.first <<endl;
    for (int k = 0; k < n; k++) {
      for (auto c : ss)
        for (int i = 1 - h[k]; i < 4; i++)
          for (int j = 1 - w[k]; j < 4; j++) {
            int bit = z.second;
            for (int x = max(i, 0); x < min(i + h[k], 4); x++)
              for (int y = max(j, 0); y < min(j + w[k], 4); y++) {
                if (s[x][y] == c)
                  bit = bit | (1 << ((y)*4 + x));
                else if (bit & ((1 << ((y)*4 + x))))
                  bit -= (1 << ((y)*4 + x));
              }
            if (dp[bit] < 0)
              pq.push(mp(z.first + 1, bit));
          }
    }
  }

  cout << dp[(1 << 16) - 1] << endl;

  return 0;
}