40. Combination Sum II

// https://leetcode.com/problems/combination-sum-ii/
// Similar to subsets II problem
function combinationSum2(candidates, target) {
	const result = []
	candidates = candidates.sort((a, b) => a - b)

	function cHelper(i, slate, sum) {
		// Backtracking case with sum == target
		if (sum === target) {
			result.push(slate.slice(0))
			return
		}
		// Backtracking case + base case
		if (sum > target || i === candidates.length) return

		let count = 1,
			j = i + 1
		while (j < candidates.length && candidates[j] === candidates[i]) {
			count++
			j++
		}

		for (let copies = 0; copies < count + 1; copies++) {
			for (let op = 0; op < copies; op++) {
				slate.push(candidates[i])
				sum += candidates[i]
			}

			cHelper(count + i, slate, sum)

			for (let op = 0; op < copies; op++) {
				slate.pop()
				sum -= candidates[i]
			}
		}
	}

	cHelper(0, [], 0)
	return result
}

console.log(combinationSum2([10, 1, 2, 7, 6, 1, 5], 8))