GO 实现二分查找

package main

import "fmt"

func main() {
   array := []int{1, 5, 9, 15, 81, 89, 123, 189, 333}
   target := 500
   result := BinarySearch(array, target, 0, len(array)-1)
   fmt.Println(target, result)
   target = 189
   result = BinarySearch(array, target, 0, len(array)-1)
   fmt.Println(target, result)
}

func BinarySearch(array []int, target int, l, r int) int {
   if l > r {
      //出界了， 找不到
      return -1
   }
   //从中间开始找
   mid := (l + r) / 2
   middleNum := array[mid]
   if middleNum == target {
      return mid //找到了
   } else if middleNum > target {
      //中间的数比目标大，从左边开始找
      return BinarySearch(array, target, l, mid-1)
   } else {
      //中间的数比目标还小，从右边开始找
      return BinarySearch(array, target, mid+1, r)
   }

}