def binary_search(array,key,left,right): if left>right: return -1 mid=(right+left)//2 if key==array[mid]: return mid i=0 if key<array[mid]: i+=1 print("subarray at step {} : {}".format(i,array[left:mid])) return binary_search(array,key,left,mid-1) elif key>array[mid]: i+=1 print("subarray at step {} : {}".format(i,array[mid:right])) return binary_search(array,key,mid+1,right)array=[1,2,3,4,5,6,7,8,9,11,22,33,44,55,66,77,88,99,222,333]res= binary_search(array,88,0,len(array))print(res if res!=-1 else "Not found")在這個二分搜索代碼中，我無法弄清楚為什么計數器不工作。每次打印i 1。計數器不會增加。我究竟做錯了什么？謝謝。
2 回答
德瑪西亞99
TA貢獻1770條經驗 獲得超3個贊
i 被打印為 1，因為每次調用時，i 在 binary_search 函數中都被設置為 0。嘗試將 i 的初始化移到函數之外。
def binary_search(array,key,left,right):
global i
if left>right:
return -1
mid=(right+left)//2
if key==array[mid]:
return mid
# i=0
if key<array[mid]:
i+=1
print("subarray at step {} : {}".format(i,array[left:mid]))
return binary_search(array,key,left,mid-1)
elif key>array[mid]:
i+=1
print("subarray at step {} : {}".format(i,array[mid:right]))
return binary_search(array,key,mid+1,right)
i =0
array=[1,2,3,4,5,6,7,8,9,11,22,33,44,55,66,77,88,99,222,333]
res= binary_search(array,88,0,len(array))
您需要更改變量 i 的范圍以使其成為全局變量。
海綿寶寶撒
TA貢獻1809條經驗 獲得超8個贊
使i作為全局變量并分配有價值的調用全局關鍵字
i = 0
def binary_search(array,key,left,right):
if left>right:
return -1
mid=(right+left)//2
# i=0
if key==array[mid]:
return f'it found position {mid}'
if key<array[mid]:
global i
i = i+1
print("subarray at step {} : {}".format(i,array[left:mid]))
return binary_search(array,key,left,mid-1)
elif key>array[mid]:
i+=1
print("subarray at step {} : {}".format(i,array[mid:right]))
return binary_search(array,key,mid+1,right)
array=[1,2,3,4,5,6,7,8,9,11,22,33,44,55,66,77,88,99,222,333]
res= binary_search(array,88,0,len(array))
print(len(array))
print(res if res!=-1 else "Not found")
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