力扣

    func findRepeatNumber(nums []int) int {
    a := make(map[int]int)
    for _, num := range nums {
        _, v := a[num]
        if v {
            return num
        } else {
            a[num] = num
        }
    }
    return 0
}
func findRepeatNumber1(nums []int) int {
    var sign [100000]bool
    for _, num := range nums {
        if sign[num] {
            return num
        }
        sign[num] = true
    }
    return 0
}