Noip2002-Universal Group Rematch-third question-select number

Title DescriptionDescription n integers known as x1,x2,..., xn, and an integer k (k<n). Add any of the k integers from n integers to get a series of sum. For example, when n=4,k=3,4 integers are 3,7,12,19, all combinations can be combined with their and:
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). input/output format input/output Input Format:
Keyboard input, in the form of:
N, K (1<=n<=20,k<n)
X1,X2,...,XN (1<=xi<=5000000)
output Format:
Screen output in the form of:
An integer (the number of species that satisfies the condition). input and Output sample sample Input/output sample Test point # # Input Sample:

4 3
3 7 12 19

Sample output:

1

Idea: Analog, not explained!

The code is as follows:

1 //use array input to save the flags used for each number, and use array A to save the entered numbers2#include <stdio.h>3#include <math.h>4#include <string.h>5 intsort=0, n,k,a[ +]; 6 intSushu (intX//is the prime number to return 1, not to return 07 {    8     intI,y; 9y=sqrt (x); Ten      for(i=2; i<=y;i++)     One         if(x%i==0)     A             return 0;  -     return 1;  - }     the voidFintInput[],intPosintM//f (Array to be manipulated, location, number of M selected) - {     -     if(m==0)     -     {     +         intj,sum=0;  -          for(j=0; j<n;j++)     +             if(input[j]==1)     Asum+=A[j];  at         if(Sushu (sum) = =1)     -sort++;  -         return;  -     }     -     Else     -     {     in         inti;  -          for(i=pos;i<n;i++)     to         {     +             if(input[i]==0)     -input[i]=1;  theF (input,i+1, M-1);  *input[i]=0;  $         }    Panax Notoginseng     }     -     return;  the }     + intMain () A {     the     intinput[ +],i;  +scanf"%d%d",&n,&k);  -      for(i=0; i<n;i++)     $scanf"%d",&A[i]);  $memset (Input,0,sizeof(int)* +);  -F (Input,0, K);  -printf"%d\n", sort);  the     return 0;  -}

Noip2002-Universal Group Rematch-third question-select number