Submission #310433

#	Time	Username	Problem	Language	Result	Execution time	Memory
310433		VROOM_VARUN	Skyscraper (JOI16_skyscraper)	C++14	15 / 100	146 ms	260648 KiB

skyscraper

/*
ID: varunra2
LANG: C++
TASK: skycraper
*/

#include <bits/stdc++.h>
using namespace std;

#ifdef DEBUG
#include "lib/debug.h"
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#define debug_arr(...) \
  cerr << "[" << #__VA_ARGS__ << "]:", debug_arr(__VA_ARGS__)
#pragma GCC diagnostic ignored "-Wsign-compare"
//#pragma GCC diagnostic ignored "-Wunused-parameter"
//#pragma GCC diagnostic ignored "-Wunused-variable"
#else
#define debug(...) 42
#endif

#define EPS 1e-9
#define IN(A, B, C) assert(B <= A && A <= C)
#define INF (int)1e9
#define MEM(a, b) memset(a, (b), sizeof(a))
#define MOD 1000000007
#define MP make_pair
#define PB push_back
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.end(), cont.begin()
#define x first
#define y second
#define int long long

const double PI = acos(-1.0);
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef map<int, int> MPII;
typedef multiset<int> MSETI;
typedef set<int> SETI;
typedef set<string> SETS;
typedef vector<int> VI;
typedef vector<PII> VII;
typedef vector<VI> VVI;
typedef vector<string> VS;

#define rep(i, a, b) for (int i = a; i < (b); ++i)
#define trav(a, x) for (auto& a : x)
#define sz(x) (int)(x).size()
typedef pair<int, int> pii;
typedef vector<int> vi;
#pragma GCC diagnostic ignored "-Wsign-compare"
// util functions

const int N = 105;
const int L = 1005;

int dp[N][N][L][3];

int n, l;
VI vals;

void ad(int& a, int b) {
  b %= MOD;
  a += b;
  a %= MOD;
}

// int solve(int i, int cc, int sum, int bnds) {
//   if (cc == 0 or bnds == 3 or sum > l) return 0;

//   if (i == n) {
//     if (cc == 1 and sum <= l and bnds == 2) return 1;
//     return 0;
//   }

//   if (dp[i][cc][sum][bnds] != -1) return dp[i][cc][sum][bnds];

//   int nsum = sum + (2 * cc - bnds) * (vals[i] - vals[i - 1]);

//   int ret = 0;

//   ad(ret, (cc + 1 - bnds) * solve(i + 1, cc + 1, nsum, bnds));
//   ad(ret, (2 * cc - bnds) * solve(i + 1, cc, nsum, bnds));
//   ad(ret, (cc - 1) * solve(i + 1, cc - 1, nsum, bnds));
//   ad(ret, (2 - bnds) * solve(i + 1, cc + 1, nsum, bnds + 1));
//   ad(ret, (2 - bnds) * solve(i + 1, cc, nsum, bnds + 1));

//   ret %= MOD;

//   dp[i][cc][sum][bnds] = ret;

//   return ret;
// }
const int M = MOD;

long long solve(int pos, int cc, int diff, int ends) {
    if(pos == n) return (cc == 1 && diff <= l && ends == 2);
    if(cc == 0 || diff > l || ends == 3) return 0;
    long long &now = dp[pos][cc][diff][ends];
    if(~now) return now;
    
    int ndiff = diff + (vals[pos] - vals[pos - 1]) * (2 * cc - ends);
 
    now = 0;
    now = (now + (cc + 1 - ends) * solve(pos + 1, cc + 1, ndiff, ends) % M) % M;
    now = (now + (2 * cc - ends) * solve(pos + 1, cc, ndiff, ends) % M) % M;
    now = (now + (cc - 1) * solve(pos + 1, cc - 1, ndiff, ends) % M) % M;
    now = (now + (2 - ends) * solve(pos + 1, cc + 1, ndiff, ends + 1) % M) % M;
    now = (now + (2 - ends) * solve(pos + 1, cc, ndiff, ends + 1) % M) % M;
 
    return now;
}

int32_t main() {
  // #ifndef ONLINE_JUDGE
  // freopen("skycraper.in", "r", stdin);
  // freopen("skycraper.out", "w", stdout);
  // #endif
  cin.sync_with_stdio(0);
  cin.tie(0);

  cin >> n >> l;

  MEM(dp, -1);

  vals.resize(n);

  for (int i = 0; i < n; i++) {
    cin >> vals[i];
  }

  sort(all(vals));

  cout << (solve(1, 1, 0, 0) + 2 * solve(1, 1, 0, 1)) % MOD << '\n';

  return 0;
}

• Subtask 1: 0 / 5
• Subtask 2: 15 / 15
• Subtask 3: 0 / 80