Submission #239602

#	Time	Username	Problem	Language	Result	Execution time	Memory
239602		Nightlight	Skyscraper (JOI16_skyscraper)	C++14	100 / 100	230 ms	240248 KiB

skyscraper

#include <bits/stdc++.h>
#define MOD 1000000007
using namespace std;

int N, L;
int A[105];
int diff[105];
long long memo[101][101][1001][3];

long long dp(int n, int cc, int sum, int k) {
  if(sum > L) return 0;
  if(n > N) return cc == 1 && k == 2;
  if(memo[n][cc][sum][k] != -1) return memo[n][cc][sum][k];
  long long res = 0, nxt = sum + (cc * 2 - k) * diff[n];
  //ga nempel :D
  res += dp(n + 1, cc + 1, nxt, k) * (cc + 1 - k);
  //nempel 1
  if(cc > 0)
   res += dp(n + 1, cc, nxt, k) * (cc * 2 - k);
  //gabung
  if(cc > 1)
    res += dp(n + 1, cc - 1, nxt, k) * (cc - 1);
  
  if(k < 2) {
    //di ujung tapi ga gabung
    res += dp(n + 1, cc + 1, nxt, k + 1) * (2 - k);
    //di ujung nempel
    if(cc > 0)
      res += dp(n + 1, cc, nxt, k + 1) * (2 - k);
  }
  return memo[n][cc][sum][k] = res % MOD;
}

int main() {
  memset(memo, -1, sizeof(memo));
  scanf("%d %d", &N, &L);
  if(N == 1) {
    puts("1");
    return 0;
  }
  for(int i = 1; i <= N; i++) {
    scanf("%d", &A[i]);
  }
  sort(A + 1, A + N + 1);
  diff[1] = 0;
  for(int i = 2; i <= N; i++) {
    diff[i] = A[i] - A[i - 1];
  }
  cout << dp(1, 0, 0, 0) << "\n";
  cin >> N;
}

Compilation message (stderr)

skyscraper.cpp: In function 'int main()':
skyscraper.cpp:36:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d %d", &N, &L);
   ~~~~~^~~~~~~~~~~~~~~~~
skyscraper.cpp:42:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &A[i]);
     ~~~~~^~~~~~~~~~~~~

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