LintCode 89. k Sum

http://www.lintcode.com/en/problem/k-sum/

/**
 * dynamic programming
 * DP Elements:
 * 1. state:
 * dp ijt means the combinations, of picking j numbers, from the first i numbers. that sum to the t.
 *
 * 2. Init
 * dp 0j mean no number to pick, target 0 would meet, otherwise haha
 * dp i0 mean pick 0 numbers, same as above.
 *
 * 3. Func
 * dp ijt = no pick -> dp i - 1, j, t
 * pick   -> dp i - 1, j - 1, t - A[i]
 *
 * 4. Answer
 * dp len, k
 */