Submission #590930

#	Time	Username	Problem	Language	Result	Execution time	Memory
590930		messiuuuuu	Skyscraper (JOI16_skyscraper)	C++14	100 / 100	41 ms	15876 KiB

skyscraper

#include<bits/stdc++.h>
#define task "C"
#define ll long long
#define ld long double
#define fi first
#define se second
#define pb push_back
using namespace std;
const int MAXN = 1e2 + 5;
const int MAXM = 1e3 + 5;
const ll INF = 1e18 + 5;
const int MOD = 1e9 + 7;

int n, l, a[MAXN];

void Input()
{
    cin >> n >> l;
    for (int i = 1; i <= n; i++)
        cin >> a[i];
}

int mul(int a, int b)
{
    return 1ll * a * b % MOD;
}

void add(int& a, int b)
{
    a += b;
    if (a > MOD)
        a -= MOD;
}

int dp[MAXN][MAXN][MAXM][3];

void Solve()
{
    sort (a + 1, a + n + 1);
    dp[1][1][0][0] = dp[1][1][0][2] = 1;
    dp[1][1][0][1] = 2;
    for (int i = 1; i < n; i++)
    {
        for (int j = 1; j <= i; j++)
        {
            for (int k = 0; k <= l; k++)
            {
                for (int z = 0; z <= 2; z++)
                {
                    int nk = k + (2 * j - z) * (a[i + 1] - a[i]);
                    if (!dp[i][j][k][z] || nk < 0 || nk > l)
                        continue;

                    add(dp[i + 1][j + 1][nk][z], mul(dp[i][j][k][z], j + 1 - z));

                    add(dp[i + 1][j][nk][z], mul(dp[i][j][k][z], 2 * j - z));

                    if (j >= 2)
                        add(dp[i + 1][j - 1][nk][z], mul(dp[i][j][k][z], j - 1));

                    if (z < 2)
                    {
                        add(dp[i + 1][j][nk][z + 1], mul(dp[i][j][k][z], 2 - z));
                        add(dp[i + 1][j + 1][nk][z + 1], mul(dp[i][j][k][z], 2 - z));
                    }
                }
            }
        }
    }

    int ans = 0;
    for (int i = 0; i <= l; i++)
        add(ans, dp[n][1][i][2]);
    cout << ans;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    if (fopen(task".INP","r"))
    {
        freopen(task".INP","r",stdin);
        //freopen(task".OUT","w",stdout);
    }
    Input();
    Solve();
}

Compilation message (stderr)

skyscraper.cpp: In function 'int main()':
skyscraper.cpp:83:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   83 |         freopen(task".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

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