Submission #484198

#	Time	Username	Problem	Language	Result	Execution time	Memory
484198		n0sk1ll	Kangaroo (CEOI16_kangaroo)	C++14	100 / 100	12 ms	14080 KiB

kangaroo

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#define FAST ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);cerr.tie(0)
#define mp make_pair
#define xx first
#define yy second
#define pb push_back
#define pf push_front
#define popb pop_back
#define popf pop_front
#define all(x) (x).begin(),(x).end()
#define inv(n) power((n), mod - 2)
#define ff(i,a,b) for (int (i) = (a); (i) < (b); (i)++)
#define fff(i,a,b) for (int (i) = (a); (i) <= b; (i)++)
#define bff(i,a,b) for (int (i) = (b)-1; (i) >= (a); (i)--)
#define bfff(i,a,b) for (int (i) = (b); (i) >= (a); (i)--)
#define sum_overflow(a,b) __builtin_add_overflow_p ((a), (b), (__typeof__ ((a) + (b))) 0)
#define mul_overflow(a,b) __builtin_mul_overflow_p ((a), (b), (__typeof__ ((a) + (b))) 0)

using namespace std;
long double typedef ld;
unsigned int typedef ui;
long long int typedef li;
pair<int,int> typedef pii;
pair<li,li> typedef pli;
pair<ld,ld> typedef pld;
vector<vector<int>> typedef graph;
unsigned long long int typedef ull;
//const int mod = 998244353;
const int mod = 1000000007;

using namespace __gnu_pbds;
template <class T> using oset = tree<T, null_type,less<T>, rb_tree_tag,tree_order_statistics_node_update>;
template <class T> using omset = tree<T, null_type,less_equal<T>, rb_tree_tag,tree_order_statistics_node_update>;







//Note to self: Check for overflow

int dp[2004][2004];

int main()
{
    int n,s,f;
    cin>>n>>s>>f;

    dp[1][1]=1; int ended=0;
    if (s==1 || f==1) ended++;

    fff(i,2,n)
    {
        fff(k,1,i)
        {
            if (i==s || i==f) dp[i][k]=(dp[i-1][k-1]+dp[i-1][k])%mod;
            else dp[i][k]=((li)(max(0,k-ended))*dp[i-1][k-1] + (li)k*dp[i-1][k+1])%mod;
        }
        if (i==s || i==f) ended++;
    }

    /*fff(i,1,n)
    {
        fff(k,1,i) cout<<dp[i][k]<<" ";
        cout<<endl;
    }*/
    cout<<dp[n][1];
}

//Note to self: Check for overflow

Compilation message (stderr)

kangaroo.cpp: In function 'int main()':
kangaroo.cpp:16:29: warning: unnecessary parentheses in declaration of 'i' [-Wparentheses]
   16 | #define fff(i,a,b) for (int (i) = (a); (i) <= b; (i)++)
      |                             ^
kangaroo.cpp:56:5: note: in expansion of macro 'fff'
   56 |     fff(i,2,n)
      |     ^~~
kangaroo.cpp:16:29: warning: unnecessary parentheses in declaration of 'k' [-Wparentheses]
   16 | #define fff(i,a,b) for (int (i) = (a); (i) <= b; (i)++)
      |                             ^
kangaroo.cpp:58:9: note: in expansion of macro 'fff'
   58 |         fff(k,1,i)
      |         ^~~

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