题目：

题解：

func combinationSum2(candidates []int, target int) (ans [][]int) {sort.Ints(candidates)var freq [][2]intfor _, num := range candidates {if freq == nil || num != freq[len(freq)-1][0] {freq = append(freq, [2]int{num, 1})} else {freq[len(freq)-1][1]++}}var sequence []intvar dfs func(pos, rest int)dfs = func(pos, rest int) {if rest == 0 {ans = append(ans, append([]int(nil), sequence...))return}if pos == len(freq) || rest < freq[pos][0] {return}dfs(pos+1, rest)most := min(rest/freq[pos][0], freq[pos][1])for i := 1; i <= most; i++ {sequence = append(sequence, freq[pos][0])dfs(pos+1, rest-i*freq[pos][0])}sequence = sequence[:len(sequence)-most]}dfs(0, target)return
}func min(a, b int) int {if a < b {return a}return b
}