#include <bits/stdc++.h>
using namespace std;
//------------------------------DEFINE------------------------------
//******************************************************************
#define IOS ios_base::sync_with_stdio(false); cin.tie(0),cout.tie(0)
#define ll long long
#define pb push_back
#define F first
#define S second
#define INF 1e18
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
#define pii pair<int,int>
#define pll pair<ll,ll>
#define OK cout<<"Ok"<<endl;
#define MOD (ll)(1e9+7)
#define endl "\n"
//******************************************************************
//----------------------------FUNCTION------------------------------
//******************************************************************
ll gcd(ll a,ll b){
if(a>b) swap(a,b);
if(a==0) return a+b;
return gcd(b%a,a);
}
ll lcm(ll a,ll b){
return a/gcd(a,b)*b;
}
bool is_prime(ll n){
ll k=sqrt(n);
if(n==2) return true;
if(n<2||n%2==0||k*k==n) return false;
for(int i=3;i<=k;i+=2){
if(n%i==0){
return false;
}
}
return true;
}
//*****************************************************************
//--------------------------MAIN-CODE------------------------------
const int mxn=2000+5;
ll t=1,n,l,r,dp[2][mxn][mxn];
void solve(){
cin>>n>>l>>r;
dp[0][1][l]=1;
dp[1][1][l]=1;
for(int i=2;i<=n;i++){
for(int j=1;j<=n;j++){
if(j==l||(i<n&&j==r)){
continue;
}
for(int k=1;k<j;k++){
if(k==r){
continue;
}
dp[0][i][j]=(dp[1][i-1][k]+dp[0][i][j])%MOD;
}
for(int k=j+1;k<=n;k++){
if(k==r){
continue;
}
dp[1][i][j]=(dp[1][i][j]+dp[0][i-1][k])%MOD;
}
}
}
cout<<(dp[0][n][r]+dp[1][n][r])%MOD;
}
int main(){
IOS;
//cin>>t;
while(t--){
solve();
}
return 0;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
332 KB |
Output is correct |
| 2 |
Incorrect |
1 ms |
332 KB |
Output isn't correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
332 KB |
Output is correct |
| 2 |
Incorrect |
1 ms |
332 KB |
Output isn't correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
332 KB |
Output is correct |
| 2 |
Incorrect |
1 ms |
332 KB |
Output isn't correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
332 KB |
Output is correct |
| 2 |
Incorrect |
1 ms |
332 KB |
Output isn't correct |
