Submission #1203313

#	Time	Username	Problem	Language	Result	Execution time	Memory
1203313		CodeLakVN	Magneti (COCI21_magneti)	C++20	110 / 110	70 ms	121412 KiB

Main

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

#define task "21_magneti"
#define no "NO"
#define yes "YES"
#define F first
#define S second
#define vec vector
#define _mp make_pair
#define ii pair<int, int>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define evoid(val) return void(std::cout << val)
#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FOD(i, b, a) for(int i = (b); i >= (a); --i)

const int MAX_L = (int)1e4 + 4;
const int MOD = (int)1e9 + 7;

int n, length;
int radius[55];

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

namespace sub1 {
    bool valid() {
        FOR(i, 1, n) if (radius[i] != radius[1]) return false;
        return true;
    }

    int dp[55][MAX_L], pre[MAX_L];

    void solve() {
        memset(dp, 0, sizeof(dp));
        FOR(i, 1, length) dp[1][i] = 1, pre[i] = i;
        FOR(i, 2, n) {
            FOR(l, 1, length) if (l > radius[1]) dp[i][l] = pre[l - radius[1]];  
            FOR(l, 1, length) pre[l] = (pre[l - 1] + dp[i][l]) % MOD;
        }

        int ans = 1;
        FOR(i, 1, n) ans = 1LL * ans * i % MOD;
        int sum = 0;
        FOR(l, 1, length) sum = (sum + dp[n][l]) % MOD;
        ans = 1LL * ans * sum % MOD;

        cout << ans << "\n";
    }
}

namespace subFull {
    int dp[55][55][MAX_L];
    int C[MAX_L][55];

    int mul(int x, int y) {
        return 1LL * x * y % MOD;
    }
    
    int choose(int k, int n) {
        if (n == k || k == 0) return 1;
        if (k > n) return 0;
        if (C[n][k] != -1)  return C[n][k];
        return (C[n][k] = (choose(k - 1, n - 1) + choose(k, n - 1)) % MOD);
    }

    void solve() {
        sort(radius + 1, radius + n + 1);
        memset(dp, 0, sizeof(dp));
        memset(C, -1, sizeof(C));
        
        dp[0][0][0] = 1;
        FOR(i, 0, n - 1) FOR(j, 0, i) FOR(d, 0, length) if (dp[i][j][d]) {
            int cur = dp[i][j][d];
            if (d + 1 <= length) add(dp[i + 1][j + 1][d + 1], mul(cur, j + 1)); // the new one
            if (d + radius[i + 1] <= length) add(dp[i + 1][j][d + radius[i + 1]], mul(cur, j * 2)); // extend
            if (j && d + 2 * radius[i + 1] - 1 <= length) add(dp[i + 1][j - 1][d + 2 * radius[i + 1] - 1], mul(cur, j - 1)); // merge
        }

        int ans = 0;
        FOR(d, 1, length) if (dp[n][1][d]) add(ans, mul(dp[n][1][d], choose(n, length - d + n)));
        cout << ans << "\n";
    }
}

void solve() {
    cin >> n >> length;
    FOR(i, 1, n) cin >> radius[i];

    // if (sub1::valid()) sub1::solve();
    subFull::solve();
}

int32_t main() {
    if (fopen(task".inp", "r")) {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    bool multitest = 0;
    int numTest = 1;
    if (multitest) cin >> numTest;

    while (numTest--) {
        solve();
    }

    return 0;
}

/* Lak lu theo dieu nhac!!!! */

Compilation message (stderr)

Main.cpp: In function 'int32_t main()':
Main.cpp:99:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   99 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:100:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  100 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 20 / 20
• Subtask 3: 30 / 30
• Subtask 4: 50 / 50