Combination Sum

Medium

Given distinct positive integers candidates and a target, return all unique combinations that sum to target. A candidate may be reused unlimited times.

Example 1

Input:  candidates = [2,3,6,7], target = 7
Output: [[2,2,3],[7]]

Example 2

Input:  candidates = [2,3,5], target = 8
Output: [[2,2,2,2],[2,3,3],[3,5]]

Constraints

• 1 <= candidates.length <= 30
• All candidates are distinct positive integers.
• 1 <= target <= 40