Submission #981840

#	Time	Username	Problem	Language	Result	Execution time	Memory
981840		Requiem	Kangaroo (CEOI16_kangaroo)	C++17	100 / 100	29 ms	32204 KiB

kangaroo

#include<bits/stdc++.h>
#define int long long
#define pb push_back
#define fast ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
#define MOD 1000000007
#define INF 1e18
#define fi first
#define se second
#define FOR(i,a,b) for(int i=a;i<=b;i++)
#define FORD(i,a,b) for(int i=a;i>=b;i--)
#define sz(a) ((int)(a).size())
#define endl '\n'
#define pi 3.14159265359
#define TASKNAME "kangaroo"
template<typename T> bool maximize(T &res, const T &val) { if (res < val){ res = val; return true; }; return false; }
template<typename T> bool minimize(T &res, const T &val) { if (res > val){ res = val; return true; }; return false; }
using namespace std;
typedef pair<int,int> ii;
typedef pair<int,ii> iii;
typedef vector<int> vi;
const int MAXN = 2009;
int dp[MAXN][MAXN],in=0,n,s,t;
int solve(int pos,int component,int in){
//    cout<<pos<<' '<<component<<endl;
    if (pos==n+1){
        if (component==1) return 1;
        else return 0;
    }
    int &res = dp[pos][component];

    if (res != -1) return res;
    res = 0;
    if (pos==s){

        if (component>0 && (in==0 || (in>0 && (component>1 || pos==n)))) res =(res + solve(pos+1,component,in+1))%MOD;
        res = (res + solve(pos+1,component+1,in+1))%MOD;
    }
    else if (pos == t) {
        if (component>0 && (in==0 || (in>0 && (component>1 || pos==n)))) res =(res + solve(pos+1,component,in+1))%MOD;
        res =(res + solve(pos+1,component+1,in+1))%MOD;
    }
    else{
        int mulfactor = component+1 - in;
        res = (res + solve(pos+1,component+1,in) * mulfactor)%MOD; // tao 1 tplt moi
        if (component>1){ //noi 2 tplt
            res = (res + solve(pos+1,component-1,in) * (component-1))%MOD;
        }
    }
    return res;
}
main()
{
    fast;
 //   freopen(TASKNAME".inp","r",stdin);
  //  freopen(TASKNAME".out","w",stdout);
    cin>>n>>s>>t;
    memset(dp,-1,sizeof(dp));
    int ans = solve(1,0,0);
    cout<<ans<<endl;
}

Compilation message (stderr)

kangaroo.cpp:51:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   51 | main()
      | ^~~~

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