{ "data": { "question": { "questionId": "39", "questionFrontendId": "39", "boundTopicId": null, "title": "Combination Sum", "titleSlug": "combination-sum", "content": "

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. You may return the combinations in any order.

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The same number may be chosen from candidates an unlimited number of times. Two combinations are unique if the frequency of at least one of the chosen numbers is different.

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It is guaranteed that the number of unique combinations that sum up to target is less than 150 combinations for the given input.

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Example 1:

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\nInput: candidates = [2,3,6,7], target = 7\nOutput: [[2,2,3],[7]]\nExplanation:\n2 and 3 are candidates, and 2 + 2 + 3 = 7. Note that 2 can be used multiple times.\n7 is a candidate, and 7 = 7.\nThese are the only two combinations.\n
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Example 2:

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\nInput: candidates = [2,3,5], target = 8\nOutput: [[2,2,2,2],[2,3,3],[3,5]]\n
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Example 3:

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\nInput: candidates = [2], target = 1\nOutput: []\n
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Constraints:

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