#include<bits/stdc++.h>
typedef long long ll;
typedef long double lld;
using namespace std;
#define endl "\n"
#define fi first
#define se second
#define MEMS(a,b) memset(a,b,sizeof(a))
#define _ ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define __ freopen("kangaroo.in","r",stdin);freopen("kangaroo.out","w",stdout);
#define all(c) c.begin(),c.end()
#define pii pair<int, int>
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
int rand(int l, int r)
{
uniform_int_distribution<int> uid(l, r);
return uid(rng);
}
#define tr(...) cout<<__FUNCTION__<<' '<<__LINE__<<" = ";trace(#__VA_ARGS__, __VA_ARGS__)
template<typename S, typename T>
ostream& operator<<(ostream& out,pair<S,T> const& p){out<<'('<<p.fi<<", "<<p.se<<')';return out;}
template<typename T>
ostream& operator<<(ostream& out,vector<T> const& v){
ll l=v.size();for(ll i=0;i<l-1;i++)out<<v[i]<<' ';if(l>0)out<<v[l-1];return out;}
template <typename T>
ostream &operator<<(ostream &out, set<T> const &v) {
for (auto i = v.begin(); i != v.end(); i++)
out << (*i) << ' ';
return out;
}
template <typename T>
ostream &operator<<(ostream &out, multiset<T> const &v) {
for (auto i = v.begin(); i != v.end(); i++)
out << (*i) << ' ';
return out;
}
template <typename T, typename V>
ostream &operator<<(ostream &out, map<T, V> const &v) {
for (auto i = v.begin(); i != v.end(); i++)
out << "\n" << (i->first) << ":" << (i->second);
return out;
}
template<typename T>
void trace(const char* name, T&& arg1){cout<<name<<" : "<<arg1<<endl;}
template<typename T, typename... Args>
void trace(const char* names, T&& arg1, Args&&... args){
const char* comma = strchr(names + 1, ',');cout.write(names, comma-names)<<" : "<<arg1<<" | ";trace(comma+1,args...);}
const int N = 2020;
const int MOD = 1e9 + 7;
int n, cs, cf;
int dp[N][N];
int f(int ind, int comp) {
if (ind > n) return (comp == 1);
if (comp < 0) return 0;
int &ans = dp[ind][comp];
if (ans != -1) return ans;
ans = 0;
if (ind == cs || ind == cf) {
ans = f(ind + 1, comp + 1); // make a new component
ans = (0LL + ans + f(ind + 1, comp)) % MOD; // just join with the existing component
return ans;
} else {
// joining existing components;
ans = (1LL * f(ind + 1, comp - 1) * (comp - 1)) % MOD;
// adding new component;
int pos = comp + 1; // available positions.
if (ind > cs) pos--;
if (ind > cf) pos--;
ans = (0LL + ans + 1LL * f(ind + 1, comp + 1) * pos) % MOD;
return ans;
}
}
int solve() {
cin >> n >> cs >> cf;
MEMS(dp, -1);
cout << f(1, 0) << endl;
return 0;
}
int32_t main(){ _
__
int t;
// cin >> t;
t = 1;
while (t--) solve();
}
Compilation message
kangaroo.cpp: In function 'int32_t main()':
kangaroo.cpp:12:19: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
#define __ freopen("kangaroo.in","r",stdin);freopen("kangaroo.out","w",stdout);
~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
kangaroo.cpp:92:1: note: in expansion of macro '__'
__
^~
kangaroo.cpp:12:52: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
#define __ freopen("kangaroo.in","r",stdin);freopen("kangaroo.out","w",stdout);
~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
kangaroo.cpp:92:1: note: in expansion of macro '__'
__
^~
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
14 ms |
16256 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
14 ms |
16256 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
14 ms |
16256 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Incorrect |
14 ms |
16256 KB |
Output isn't correct |
| 2 |
Halted |
0 ms |
0 KB |
- |
