Submission #372812

#	Time	Username	Problem	Language	Result	Execution time	Memory
372812		MiricaMatei	Skyscraper (JOI16_skyscraper)	C++14	100 / 100	106 ms	2924 KiB

skyscraper

#include <bits/stdc++.h>

using namespace std;

const int MAXN = 105;
const int MAXL = 1005;
const int MOD = 1e9 + 7;

int a[MAXN];
int dp[3][MAXN][MAXL][3];

int main() {
  //freopen("date.in", "r", stdin);
  //freopen("date.out", "w", stdout);

  int n, l;
  scanf("%d%d", &n, &l);
  for (int i = 1; i <= n; ++i)
    scanf("%d", &a[i]);

  sort(a + 1, a + n + 1);
  reverse(a + 1, a + n + 1);

  dp[1][0][0][0] = 1;
  dp[1][0][0][1] = 2;
  dp[1][0][0][2] = 1;
  for (int i = 1; i < n; ++i) {
    int dif = a[i] - a[i + 1];
    int pv = i & 1;
    int nx = (pv ^ 1);
    for (int j = 0; j <= i + 1; ++j) {
      for (int s = 0; s <= l; ++s) {
        for (int e = 0; e <= 2; ++e) {
          int ns = s + dif * (2 * j + 2 - e);
          if (ns > l)
            continue;
          if (j - 1 >= 0)
            dp[nx][j - 1][ns][e] = (dp[nx][j - 1][ns][e] + 1LL * j * dp[pv][j][s][e]) % MOD;
          dp[nx][j][ns][e] = (dp[nx][j][ns][e] + 1LL * (2 * j + 2 - e) * dp[pv][j][s][e]) % MOD;
          dp[nx][j + 1][ns][e] = (dp[nx][j + 1][ns][e] + 1LL * (j + 2 - e) * dp[pv][j][s][e]) % MOD;

          if (e + 1 <= 2)
            dp[nx][j][ns][e + 1] = (dp[nx][j][ns][e + 1] + 1LL * (2 - e) * dp[pv][j][s][e]) % MOD;
          if (e + 1 <= 2)
            dp[nx][j + 1][ns][e + 1] = (dp[nx][j + 1][ns][e + 1] + 1LL * (2 - e) * dp[pv][j][s][e]) % MOD;
        }
      }
    }
    memset(dp[pv], 0, sizeof(dp[pv]));
  }

  int ans = 0;
  for (int i = 0; i <= l; ++i)
    ans = (ans + dp[n & 1][0][i][2]) % MOD;

  printf("%d\n", ans);

  return 0;
}

Compilation message (stderr)

skyscraper.cpp: In function 'int main()':
skyscraper.cpp:17:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   17 |   scanf("%d%d", &n, &l);
      |   ~~~~~^~~~~~~~~~~~~~~~
skyscraper.cpp:19:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   19 |     scanf("%d", &a[i]);
      |     ~~~~~^~~~~~~~~~~~~

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