递归二分查找
def binsearch(array,low,high,k): if low <= high: mid=(low+high)//2 if array[mid]==k: return mid elif k>array[mid]: return binsearch(array,mid+1,high,k) else: return binsearch(array,low,mid-1,k) else: return -1
非递归二分查找
def binSearch(array,k): low=0 high=len(array)-1 while low<=high: mid=(low+high)//2 if array[mid]==k: return mid elif array[mid]>k: high=mid-1 else: low=mid+1 return -1
带重复元素的有序数组返回查找元素第一次出现的位置
def bSearch(arr,k): if len(arr)==0: return -1 low=0 high=len(arr)-1 while low<=high: mid=(low+high)//2 if arr[mid]>k: while mid>low and arr[mid]==arr[mid-1]: mid-=1 high=mid-1 elif arr[mid]<k: while mid<high and arr[mid]==arr[mid+1]: mid+=1 low=mid+1 else: while mid>low and arr[mid]==arr[mid-1]: mid-=1 return mid
return -1