折半尋找演算法的變形情況; 前後端各自有序，整體無序

```package mainimport ("fmt")// 一分為2， 肯定有一半是有序的func BinarySearchDef(data []int, key int, low int, high int) int {if len(data) == 0 {return -1}// 注意臨界值for low <= high {mid := low + (high-low)/2fmt.Println(mid)fmt.Println(data[mid])if key == data[mid] {return mid}// 如果 key 比中間值小if key < data[mid] {if key == data[low] {return low}//如果key 比中間值小，但是比 low 位置上的值大if key > data[low] {// 如果 key比中間值小， 比low位置上的值大， 同時 low 到 mid 之間的元素是無序的if mid-1 >= low && data[low] >= data[mid-1] {return BinarySearchDef(data, key, low, mid-1)}// 有序則反查另一半high = mid - 1}if key < data[low] {if mid-1 >= low && data[low] >= data[mid-1] {return BinarySearchDef(data, key, low, mid-1)}low = mid + 1}}if key > data[mid] {if key == data[high] {return high}if key > data[high] {if mid+1 <= high && data[mid+1] >= data[high] {return BinarySearchDef(data, key, mid+1, high)}// 有序則反查另一半, 因為該部分中肯定無對應的值high = mid - 1}if key < data[high] {if mid+1 <= high && data[mid+1] >= data[high] {return BinarySearchDef(data, key, mid+1, high)}low = mid + 1}}}return -1}func main() {data := []int{100, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 121, 122, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10}i := BinarySearchDef(data, 3, 0, len(data)-1)fmt.Println(i)}```90 次點擊