D. Time to go back

Time limit per test: 1 second

Memory limit per test: 256 megabytes

Input: standard input

Output: the standard output

You have been out of Syria for a long time, and you recently decided to come back. You remember that you have M friends there and since you are a generous man/woman you want to buy a gift for each of them, so you went to a gift store that have N gifts, each of them has a price.

You have a lot of money so you don’t have a problem with the sum of gifts’ prices that you’ll buy, but you have K close friends among your M friends you want their gifts to be expensive so the price of each of them is at least D.

Now you are wondering, in how many different ways can you choose the gifts?

Input

The input will start with a single integer T, the number of test cases. Each test case consists of two lines.

The first line will have four integers N, M, K, D (0 ≤ N, M ≤ 200, 0 ≤ K ≤ 50, 0 ≤ D ≤ 500)

The second line will have N positive integer number, the price of each gift.

The gift price is less than 500.

Output

Print one line for each test case, the number of different ways to choose the gifts (there will be always one way at least to choose the gifts).

As the number of ways can be too large, print it modulo 1000000007.

Examples

Input

25 3 2 100 150 30 100 70 10 10 5 3 50 100 50 150 10 25 40 55 300 5 10Copy the code

Output

3, 126Copy the code

Title links: codeforces.com/gym/100952/…

There are N gifts, M friends, k of whom are very close friends and want gifts whose price is greater than D **

Price >= d (price >= d); price >= d (price >= d);

First, vis[ANS][K]* VIS [n-ANS][m-K];

 

Then vis [ans] [k + 1) * vis [n – ans] [m] – k – 1;

 

Then vis vis [ans] [k + 2) * (n – ans] [m – k – 2);

 

.

 

Until the k + 1 = = ans or m – k – 1 < 0 / / If the k + 1 = = ans the ans ran out, and the m – k – 1 < 0 is is all chose price > = d

 

Complexity O(T * n)

Here is the AC code:

1 #include <bits/stdc++.h> 2 using namespace std; 3 typedef long long ll; 4 inline ll read() 5 { 6 ll x=0,f=1; 7 char ch=getchar(); 8 while(ch<'0'||ch>'9') 9 { 10 if(ch=='-') 11 f=-1; 12 ch=getchar(); 13 } 14 while(ch>='0'&&ch<='9') 15 { 16 x=x*10+ch-'0'; 17 ch=getchar(); 18 } 19 return x*f; 20 } 21 inline void write(ll x) 22 { 23 if(x<0) 24 { 25 putchar('-'); 26 x=-x; 27 } 28 if(x>9) 29 write(x/10); 30 putchar(x%10+'0'); 31 } 32 ll vis[210][210]; 33 ll val[210]; 34 const ll mod=1000000007; 35 bool cmp(ll a,ll b) 36 { 37 return a>b; 38 } 39 int main() 40 { 41 for(int i=0; i<210; i++) 42 { 43 vis[i][0]=1; 44 for(int j=1; j<=i; j++) 45 { 46 vis[i][j]=((vis[i-1][j-1]%mod)+(vis[i-1][j]%mod))%mod; 47 } 48 } 49 ll t=read(); 50 while(t--) 51 { 52 ll ans=0,pos=0; 53 ll n=read(); 54 ll m=read(); 55 ll k=read(); 56 ll d=read(); 57 for(ll i=0; i<n; i++) 58 val[i]=read(); 59 sort(val,val+n,cmp); 60 for(ll i=0; i<n; i++) 61 { 62 if(val[i]>=d) 63 ans++; 64 else break; 65 } 66 if(n-ans==0) 67 pos=vis[ans][m]; 68 else if(ans<k||n<m) 69 pos=0; 70 else 71 { 72 for(ll i=k; i<=ans; i++) 73 { 74 if(m-i<0) 75 break; 76 pos=(pos+(vis[ans][i]*vis[n-ans][m-i])%mod)%mod; 77 } 78 } 79 write(pos); 80 printf("\n"); 81 } 82 return 0; 83}Copy the code

 

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