Submission #741034

#	Time	Username	Problem	Language	Result	Execution time	Memory
741034		urosk	Kangaroo (CEOI16_kangaroo)	C++14	0 / 100	1 ms	340 KiB

kangaroo

#define here cerr<<"===========================================\n"
#define dbg(x) cerr<<#x<<": "<<x<<endl;
#include "bits/stdc++.h"
//#include <ext/pb_ds/tree_policy.hpp>
//#include <ext/pb_ds/assoc_container.hpp>
#define ld double
#define ll long long
#define llinf 100000000000000000LL // 10^17
#define pb push_back
#define popb pop_back
#define fi first
#define sc second
#define endl '\n'
#define pll pair<ll,ll>
#define pld pair<ld,ld>
#define all(a) a.begin(),a.end()
#define ceri(a,l,r) {cerr<<#a<<": ";for(ll i_ = l;i_<=r;i_++) cerr<<a[i_]<< " ";cerr<<endl;}
#define cer(a) {cerr<<#a<<": ";for(ll x_ : a) cerr<<x_<< " ";cerr<<endl;}
#define yes cout<<"YES"<<endl
#define no cout<<"NO"<<endl

#define daj_mi_malo_vremena ios_base::sync_with_stdio(false);cerr.tie(0);cout.tie(0);cin.tie(0);

using namespace std;
//using namespace __gnu_pbds;
#define mod 1000000007
ll add(ll x,ll y){
    x+=y;
    if(x<0){
        x%=mod;
        x+=mod;
    }else{
        if(x>=mod) x%=mod;
    }
    return x;
}
ll mul(ll a,ll b){
	ll ans = (a*b)%mod;
	if(ans<0) ans+=mod;
	return ans;
}
ll po(ll x,ll y){
    if(y==0) return 1LL;
    ll ans = po(x,y/2);
    ans = mul(ans,ans);
    if(y&1) ans = mul(ans,x);
    return ans;
}
ll inv(ll x){return po(x,mod-2);}

#define maxn 2005
ll n;
ll st,en;
ll dp[maxn][maxn];
void tc(){
    cin >> n >> st >> en;
    dp[1][1] = 1;
    for(ll i = 2;i<=n;i++){
        for(ll j = 1;j<=n;j++){
            if(i==st||i==en) dp[i][j] = add(dp[i-1][j],dp[i-1][j-1]);
            else{
                dp[i][j] = add(dp[i][j],mul(j+2-(i>st)-(i>en),dp[i-1][j+1]));
                dp[i][j] = add(dp[i][j],mul(j+1-(i>st)-(i>en),dp[i-1][j-1]));
            }
        }
    }
    cout<<dp[n][1]<<endl;
}
int main(){
	daj_mi_malo_vremena
    int t; t = 1;
    while(t--){
        tc();
    }
	return 0;
}

• Subtask 1: 0 / 6
• Subtask 2: 0 / 30
• Subtask 3: 0 / 15
• Subtask 4: 0 / 49