2002 Select number

Title Description Description

n integers are known to x1,x2,..., xn, and an integer k (k 3+7+12=22 3+7+19=29 7+12+19=38 3+12+19=34.
Now, ask you to figure out how many kinds of numbers are in total.
For example, in the above example, there is only one and a prime number: 3+7+19=29).

Enter a description Input Description

Keyboard input, in the form of:
N, K (1<=n<=20,k X1,X2,...,XN (1<=xi<=5000000)

Output description Output Description

Screen output in the form of:
An integer (the number of species that satisfies the condition).

Sample input Sample Input

4 3
3 7 12 19

Sample output Sample Output

1

Data range and Tips Data Size & Hint

(1<=n<=20,k (1<=xi<=5000000)

Exercises

Search + primes.

Recursive search for each number: two possible (optional), choose to add to the inside, do not choose to skip. Finally, we will find some and, judging these and is not a prime number on the line.

var n,m,i,ans:longint;

A:array[0..21]of Longint;

Procedure Dfs (K,s,sum:longint);

var i:longint;

Begin

If S=m Then

Begin

For i:=2 to Trunc (sqrt (sum)) do

If sum mod i=0 then exit;

Inc (ANS);

Exit

End

If K=n+1 then exit;

DFS (K+1,s+1,sum+a[k]);

DFS (k+1,s,sum);

End

Begin

READLN (N,M);

For I:=1 to n do read (A[i]);

DFS (1,0,0);

Write (ANS);

End.

2002 Select number