Submission #385919

#	Time	Username	Problem	Language	Result	Execution time	Memory
385919		Vladth11	Kangaroo (CEOI16_kangaroo)	C++14	100 / 100	40 ms	23040 KiB

kangaroo

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define debug(x) cerr << #x << " " << x << "\n"
#define debug_with_space(x) cerr << #x << " " << x << " "

using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef pair <ll, ll> pii;
typedef pair <long double, pii> muchie;
typedef tree <ll, null_type, less_equal <ll>, rb_tree_tag, tree_order_statistics_node_update> OST;

const ll NMAX = 201;
const ll INF = (1LL << 60);
const ll MOD = 1000000007;
const ll BLOCK = 225;
const ll base = 31;
const ll nr_of_bits = 21;

ll dp[2001][2001];

void add(ll &x, ll v) {
    x += v;
    x %= MOD;
}

int main() {
    int n, a, b, i;
    cin >> n >> a >> b;
    dp[1][1] = 1;
    for(int i = 1; i <= n; i++) {
        for(int j = 1; j <= i; j++) {
            if(i == a) {
                add(dp[i][j], dp[i - 1][j]);///adaugam ori la ce mai din stanga componenta
                add(dp[i][j], dp[i - 1][j - 1]); ///ori ne facem noi o componenta noua
            } else if(i == b) {
                ///same story ca la a
                add(dp[i][j], dp[i - 1][j]);
                add(dp[i][j], dp[i - 1][j - 1]);
            } else {
                add(dp[i][j], (dp[i - 1][j + 1] * j) % MOD); ///mergeuim doua
                add(dp[i][j], (dp[i - 1][j - 1] * ((j - 2) + (i < a) + (i < b))) % MOD); ///facem o comp noua
            }
        }
    }
    cout << dp[n][1];
    return 0;
}

Compilation message (stderr)

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:29:18: warning: unused variable 'i' [-Wunused-variable]
   29 |     int n, a, b, i;
      |                  ^

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