Submission #1165814

#	Time	Username	Problem	Language	Result	Execution time	Memory
1165814		nhphuc	Skyscraper (JOI16_skyscraper)	C++20	15 / 100	2 ms	1348 KiB

skyscraper

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

#define int long long

const int N = 107;
const int L = 1007;
const int mod = 1e9 + 7;

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

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

int n, l, a[N], dp[N][N][L][3], ans = 0;

int32_t main (){
    ios::sync_with_stdio(false); cin.tie(nullptr);
    if (fopen ("test.inp", "r")){
        freopen ("test.inp", "r", stdin);
        freopen ("test.out", "w", stdout);
    }
    cin >> n >> l;
    for (int i = 1; i <= n; ++i){
        cin >> a[i];
    }
    sort(a + 1, a + n + 1);
    dp[0][0][0][0] = 1;
    a[n + 1] = 10 * n;
    for (int i = 1; i <= n; ++i){
        for (int j = 1; j <= n; ++j){
            for (int k = 0; k <= l; ++k){
                for (int e = 0; e <= 2; ++e){
                    int cost = (2 * j - e) * (a[i + 1] - a[i]);
                    if (cost > k){
                        continue;
                    }
                    // case 1: add new component not contains endpoint
                    add(dp[i][j][k][e], dp[i - 1][j - 1][k - cost][e]);
                    // case 2: merge into a component but not be an endpoint
                    add(dp[i][j][k][e], mul(dp[i - 1][j][k - cost][e], 2 * j - e));
                    // case 3: add new component contains endpoint
                    if (e >= 1){
                        add(dp[i][j][k][e], mul(dp[i - 1][j - 1][k - cost][e - 1], 3 - e));
                    }
                    // case 4: merge into a component and be an endpoint
                    if (e == 1){
                        add(dp[i][j][k][e], mul(2 * j, dp[i - 1][j][k - cost][e - 1]));
                    }
                    if (e == 2){
                        if (i == n){
                            add(dp[i][j][k][e], dp[i - 1][j][k - cost][e - 1]);
                        } else 
                        if (j > 1){
                            add(dp[i][j][k][e], mul(dp[i - 1][j][k - cost][e - 1], j - 1));
                        }
                    }
                    // case 5: insert to join 2 component
                    if (e == 2){
                        if (i == n){
                            add(dp[i][j][k][e], dp[i - 1][j + 1][k - cost][e]);
                        } else {
                            add(dp[i][j][k][e], mul(dp[i - 1][j + 1][k - cost][e], j * (j - 1)));
                        }
                    } else {
                        if (e == 1){
                            add(dp[i][j][k][e], mul(dp[i - 1][j + 1][k - cost][e], j * j));
                        } else {
                            add(dp[i][j][k][e], mul(dp[i - 1][j + 1][k - cost][e], j * (j + 1)));
                        }
                    }
                }
            }
        }
    }
    for (int i = 0; i <= l; ++i){
        add(ans, dp[n][1][i][2]);
    }
    cout << ans << "\n";
}

Compilation message (stderr)

skyscraper.cpp: In function 'int32_t main()':
skyscraper.cpp:27:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   27 |         freopen ("test.inp", "r", stdin);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
skyscraper.cpp:28:17: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   28 |         freopen ("test.out", "w", stdout);
      |         ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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