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Combination Sum

MediumBacktracking

Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum to target. The same number may be chosen from candidates an unlimited number of times. The combinations can be returned in any order.

Example:

Input: candidates = [2,3,6,7], target = 7
Output: [[2,2,3],[7]]
Explanation: 2+2+3=7 and 7=7 are the only combinations

Constraints:

  • 1 <= candidates.length <= 30
  • 2 <= candidates[i] <= 40
  • All elements of candidates are distinct
  • 1 <= target <= 40