leetcode 401 组合问题

func readBinaryWatch(turnedOn int) []string {
    if turnedOn >= 9 {
        //panic("不能正确表示")
        return []string{}
    }
    maxHnum := 3
    maxMnum := 5
    returnData := make([]string, 0, 255)
    for hourNum, minuteNum := 0, 0; hourNum <= maxHnum; hourNum++ {
        minuteNum = turnedOn - hourNum
        if (minuteNum < 0) {
            break;
        }
        if minuteNum >maxMnum {
            continue
        }
        hourList := getHour(hourNum)
        minuteList := getMinute(minuteNum)

        for _, h := range hourList {
            for _, m := range minuteList {
                returnData = append(returnData, h + ":" + m)
            }
        } 
        
    }
    return returnData
}

func getMinute(n int) []string {
    if (n == 0) {
        return []string{"00"}
    }
    cSet := []int{1, 2, 4, 8, 16, 32}
    num := make([]string, 0, 60)

    list := sumNumItem(cSet, n)
    for _, v := range list {
        if v > 59 {
            continue
        }
        num = append(num, fmt.Sprintf("%02d", v))
    }
    return num
}

func getHour(n int) []string {
    if (n == 0) {
        return []string {"0"}
    }
    cSet := []int{1, 2, 4, 8}

    num := make([]string, 0, 60)
    list := sumNumItem(cSet, n)

    for _, v := range list {
        if v > 11 {
            continue
        }
        num = append(num, fmt.Sprintf("%d", v))
    }
    return num
}

func sumNumItem(list []int, num int) []int {
    l := len(list)
    if num > l {
        //panic("求和数量异常")
        return []int{}
    }

    if num == 1 {
        return list
    }

    returnData := make([]int, 0, 60)
    //使用位图对应方式，依次确认站位组合
    indexList := make([]int, l)
    for i := 0; i < num; i++ {
        indexList[i] = 1
    }
    returnData = append(returnData, sumIdxNum(list, indexList))
    for {
        find := false
        for i := 0; i < l - 1; i++ {
            if (indexList[i] == 1 && indexList[i + 1] == 0) {
                find = true
                indexList[i], indexList[i + 1] = 0, 1
                if indexList[0] == 0 && i > 1 {
                    resetZeroIdx(indexList, i)
                }
                returnData = append(returnData, sumIdxNum(list, indexList))
                break
            }

        }
        if !find {
            break
        }
    }
    return returnData
}

func sumIdxNum(list []int, idxSet []int) int {
    num := 0
    for idx, b := range idxSet {
        if b == 1 {
            num += list[idx]
        }
    }
    return num
}

func resetZeroIdx(idxList []int, k int) {
    sum := 0
    for i := 0; i < k; i++ {
        if idxList[i] == 1 {
            sum++
        }
    }
    //将前sum个改为1，之后的改为0
    for i := 0; i < k; i++ {
        if i < sum {
            idxList[i] = 1
        } else {
            idxList[i] = 0
        }
    }
}