Finding Sum
Finding Sum Problem Description You are given a set of N positive integers and another integer P, where P is a small prime. You need to write a program to count the number of subsets of size (cardinality) 3, the sum of whose elements is divisible by P. Since the number K of such sets can be huge, output K modulo 10007 1009 (the remainder when K is divided by 1009) Constraints N <= 500 P<50 All integers <=1000 Input Format First line two comma separated integers N, P The next line contains N comma separated integers Output One integer giving the number of subsets the sum of whose elements is divisible by P. Give result modulo 1009 Explanation Example 1 Input 4,5 5,10,15,20 Output 4 Explanation Every non empty subset of the given numbers has sum of its elements a multiple of 5. Since there are 4 subsets of size 3, the output is 4. Example 2 Input 5,5 3,7,12,13,15 Output 4 Explanation There are 4 subsets of size 3 with sum a multiple of 5: {3, 7, 15}, {12, 13, 15}, {7, 13, 15}, {3, 12, 15}, Hence the output is 4.