Submission #1273629

#	Time	Username	Problem	Language	Result	Execution time	Memory
1273629		raadbuet	캥거루 (CEOI16_kangaroo)	C++20	100 / 100	21 ms	23092 KiB

kangaroo

#include <bits/stdc++.h>
#include <bits/extc++.h> // gp_hash_table, pbds
using namespace __gnu_pbds;

#include<numeric>
using namespace std;
using ll = long long;
#define int ll
using ld = long double;
using vi = vector<int>;
#define pb push_back
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define fast ios_base::sync_with_stdio(false); cin.tie(NULL);
using pll = pair<ll, ll>;
using pi = pair<int, int>;
#define f first
#define s second
#define mp make_pair
#define deb false
#define INF 1e18
#define mod1 1000000007
#define mod2 998244353
#define N 100001
#define logN 22
#define endl "\n"
#define hash1 10007
#define hash2 1009
#define rep(i, a, b) for (int i = a; i <= b; ++i)
typedef tree<pi, null_type, less<pi>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
int tc = 1, t = 1;
 
long long binpow(long long a, long long b, long long m) {
    long long res = 1;
    while (b > 0) {
        if (b & 1)
            res = (res * a) % m;
        a = (a * a) % m;
        b >>= 1;
    }
    return res % m;
}

long long compute_hash(string const& s) {
    const int p = 31;
    const int m = 1e9 + 9;
    long long hash_value = 0;
    long long p_pow = 1;
    for (char c : s) {
        hash_value = (hash_value + (c - 'a' + 1) * p_pow) % m;
        p_pow = (p_pow * p) % m;
    }
    return hash_value;
}

int dp[2001][2001];
void solve() {
    int n, cs, cf;
    cin >> n >> cs >> cf;
    if (cs > cf) swap(cs, cf);
    dp[1][1] = 1;
    for (int i = 1; i <= n - 1; i++) {
        for (int j = 1; j <= i; j++) {
            if (i + 1 > cf) {
                dp[i + 1][j + 1] = (dp[i + 1][j + 1] + dp[i][j] * (j - 1)) % mod1; 
                dp[i + 1][j - 1] = (dp[i + 1][j - 1] + dp[i][j] * (j - 1)) % mod1;
            } else if (i + 1 == cf) {
                dp[i + 1][j] = (dp[i + 1][j] + dp[i][j]) % mod1;
                dp[i + 1][j + 1] = (dp[i + 1][j + 1] + dp[i][j]) % mod1;
            } else if (i + 1 > cs) {
                dp[i + 1][j + 1] = (dp[i + 1][j + 1] + dp[i][j] * j) % mod1; 
                dp[i + 1][j - 1] = (dp[i + 1][j - 1] + dp[i][j] * (j - 1)) % mod1;
            } else if (i + 1 == cs) {
                dp[i + 1][j] = (dp[i + 1][j] + dp[i][j]) % mod1;
                dp[i + 1][j + 1] = (dp[i + 1][j + 1] + dp[i][j]) % mod1;
            } else {
                dp[i + 1][j + 1] = (dp[i + 1][j + 1] + dp[i][j] * (j + 1)) % mod1; 
                dp[i + 1][j - 1] = (dp[i + 1][j - 1] + dp[i][j] * (j - 1)) % mod1;
            }
        }
    }
    cout << dp[n][1] << endl;
}        
 
int32_t main() {
    fast;
    //cin >> t;
    //preproces();  
    
    for (tc = 1; tc <= t; tc++) {
        solve();
    }
    return 0;
}

• Subtask 1: 6 / 6
• Subtask 2: 30 / 30
• Subtask 3: 15 / 15
• Subtask 4: 49 / 49