LintCode 562 · Backpack IV.java

Backpack with Value array:
note that: "Each item may be chosen unlimited number of times"
function:
dp[i][j] += dp[i - 1][j - A[i - 1] * k]; (when you take that ith item)
or
dp[i][j] += dp[i - 1][j]; (when you don't take that ith item)