utils

package main

func min(vs ...int) int {
    if len(vs) == 0 {
        panic("func min args empty")
    }
    m := vs[0]
    for _, n := range vs[1:] {
        if n < m {
            m = n
        }
    }
    return m
}

func max(vs ...int) int {
    if len(vs) == 0 {
        panic("func min args empty")
    }
    m := vs[0]
    for _, n := range vs[1:] {
        if n > m {
            m = n
        }
    }
    return m
}

func abs(x int) int {
    if x < 0 {
        return -x
    }
    return x
}

func reverse(nums []int) {
    for l, r := 0, len(nums)-1; l < r; l, r = l+1, r-1 {
        nums[l], nums[r] = nums[r], nums[l]
    }
}

// 递归版的二分查找虽高效，但调用传参时注意，nums 为空时 l,r 应为 0,-1，否则将 panic
func binarySearch(nums []int, l, r int, target int) int {
    if l > r {
        return -1
    }

    mid := (l + r) / 2
    switch {
    case target < nums[mid]:
        return binarySearch(nums, l, mid-1, target)
    case target > nums[mid]:
        return binarySearch(nums, mid+1, r, target)
    default:
        return mid
    }
}