HDU 3748 Equivalent mass

Problem Statement:

• Given N elements, A[N], determine if it is possible to pick exactly K of them s.t. the sum is V. But you cannot pick X^th and Y^th simultaneously, for some given pairs (X, Y). There are M such pairs.

Constraints:

• 1 <= N <= 32
• 1 <= A[i], V <= 10^9
• 0 <= M <= 6
• 0 <= K <= N