Golang | Leetcode Golang题解之第40题组合总和II

题目：

题解：

func combinationSum2(candidates []int, target int) (ans [][]int) {
    sort.Ints(candidates)
    var freq [][2]int
    for _, 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 []int
    var 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
}