Add Python code (Chapter of searching)
to the docs.
This commit is contained in:
Yudong Jin
parent
e5563b3964
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8e34be0641
@ -13,14 +13,14 @@ def binary_search(nums, target):
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# 初始化双闭区间 [0, n-1] ，即 i, j 分别指向数组首元素、尾元素
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i, j = 0, len(nums) - 1
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while i <= j:
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m = (i + j) // 2 # 计算中点索引 m
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if nums[m] < target: # 此情况说明 target 在区间 [m+1, j] 中
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m = (i + j) // 2 # 计算中点索引 m
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if nums[m] < target: # 此情况说明 target 在区间 [m+1, j] 中
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i = m + 1
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elif nums[m] > target: # 此情况说明 target 在区间 [i, m-1] 中
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j = m - 1
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else:
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return m # 找到目标元素，返回其索引
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return -1 # 未找到目标元素，返回 -1
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return m # 找到目标元素，返回其索引
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return -1 # 未找到目标元素，返回 -1
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""" 二分查找（左闭右开） """
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@ -29,16 +29,17 @@ def binary_search1(nums, target):
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i, j = 0, len(nums)
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# 循环，当搜索区间为空时跳出（当 i = j 时为空）
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while i < j:
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m = (i + j) // 2 # 计算中点索引 m
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if nums[m] < target: # 此情况说明 target 在区间 [m+1, j) 中
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m = (i + j) // 2 # 计算中点索引 m
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if nums[m] < target: # 此情况说明 target 在区间 [m+1, j) 中
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i = m + 1
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elif nums[m] > target: # 此情况说明 target 在区间 [i, m) 中
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j = m
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else: # 找到目标元素，返回其索引
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else: # 找到目标元素，返回其索引
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return m
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return -1 # 未找到目标元素，返回 -1
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return -1 # 未找到目标元素，返回 -1
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""" Driver Code """
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if __name__ == '__main__':
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target = 6
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nums = [1, 3, 6, 8, 12, 15, 23, 67, 70, 92]
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@ -46,6 +47,7 @@ if __name__ == '__main__':
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# 二分查找（双闭区间）
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index = binary_search(nums, target)
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print("目标元素 6 的索引 = ", index)
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# 二分查找（左闭右开）
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index = binary_search1(nums, target)
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print("目标元素 6 的索引 = ", index)
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@ -9,33 +9,37 @@ sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
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from include import *
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""" 哈希查找（数组） """
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def hashing_search(map,target):
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def hashing_search(mapp, target):
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# 哈希表的 key: 目标元素，value: 索引
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# 若哈希表中无此 key ，返回 -1
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return map.get(target,-1)
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return mapp.get(target, -1)
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""" 哈希查找（链表） """
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def hashing_search1(map,target):
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# 哈希表的 key: 目标元素，value: 节点对象
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def hashing_search1(mapp, target):
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# 哈希表的 key: 目标元素，value: 结点对象
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# 若哈希表中无此 key ，返回 -1
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return map.get(target,-1)
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return mapp.get(target, -1)
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""" Driver Code """
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if __name__ == '__main__':
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target = 3
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if __name__=='__main__':
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target=3
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# 哈希查找（数组）
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nums=[1, 5, 3, 2, 4, 7, 5, 9, 10, 8]
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map=dict() # 初始化哈希表
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nums = [1, 5, 3, 2, 4, 7, 5, 9, 10, 8]
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# 初始化哈希表
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mapp = {}
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for i in range(len(nums)):
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map[nums[i]]=i # key: 元素，value: 索引
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index=hashing_search(map,target)
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print("目标元素 3 的索引 = " ,index)
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mapp[nums[i]] = i # key: 元素，value: 索引
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index = hashing_search(mapp, target)
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print("目标元素 3 的索引 =", index)
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# 哈希查找（链表）
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head=list_to_linked_list(nums)
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map1=dict() # 初始化哈希表
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head = list_to_linked_list(nums)
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# 初始化哈希表
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map1 = {}
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while head:
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map1[head.val]=head # key: 结点值，value: 结点
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head=head.next
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node=hashing_search1(map1,target)
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print("目标结点值 3 的对应结点对象为 " , node)
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map1[head.val] = head # key: 结点值，value: 结点
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head = head.next
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node = hashing_search1(map1, target)
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print("目标结点值 3 的对应结点对象为", node)
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@ -9,30 +9,33 @@ sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
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from include import *
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""" 线性查找（数组） """
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def linear_search(nums,target):
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def linear_search(nums, target):
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# 遍历数组
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for i in range(len(nums)):
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if nums[i]==target: # 找到目标元素，返回其索引
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if nums[i] == target: # 找到目标元素，返回其索引
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return i
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return -1 # 未找到目标元素，返回 -1
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return -1 # 未找到目标元素，返回 -1
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""" 线性查找（链表） """
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def linear_search_by_link(head,target):
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def linear_search1(head, target):
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# 遍历链表
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while head:
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if head.val==target: # 找到目标结点，返回之
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return head
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head=head.next
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return None # 未找到目标结点，返回 None (Python为None)
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if head.val == target: # 找到目标结点，返回之
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return head
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head = head.next
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return None # 未找到目标结点，返回 None
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""" Driver Code """
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if __name__ == '__main__':
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target = 3
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if __name__=='__main__':
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target=3
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# 在数组中执行线性查找
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nums=[1, 5, 3, 2, 4, 7, 5, 9, 10, 8]
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index=linear_search(nums,target)
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print("目标元素 3 的索引 = " ,index)
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nums = [1, 5, 3, 2, 4, 7, 5, 9, 10, 8]
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index = linear_search(nums, target)
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print("目标元素 3 的索引 =", index)
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# 在链表中执行线性查找
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head=list_to_linked_list(nums)
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node=linear_search_by_link(head,target)
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print("目标结点值 3 的对应结点对象为 " ,node)
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head = list_to_linked_list(nums)
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node = linear_search1(head, target)
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print("目标结点值 3 的对应结点对象为", node)
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@ -105,7 +105,19 @@ $$
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=== "Python"
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```python title="binary_search.py"
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""" 二分查找（双闭区间） """
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def binary_search(nums, target):
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# 初始化双闭区间 [0, n-1] ，即 i, j 分别指向数组首元素、尾元素
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i, j = 0, len(nums) - 1
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while i <= j:
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m = (i + j) // 2 # 计算中点索引 m
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if nums[m] < target: # 此情况说明 target 在区间 [m+1, j] 中
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i = m + 1
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elif nums[m] > target: # 此情况说明 target 在区间 [i, m-1] 中
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j = m - 1
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else:
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return m # 找到目标元素，返回其索引
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return -1 # 未找到目标元素，返回 -1
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```
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=== "Go"
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@ -189,7 +201,20 @@ $$
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=== "Python"
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```python title="binary_search.py"
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""" 二分查找（左闭右开） """
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def binary_search1(nums, target):
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# 初始化左闭右开 [0, n) ，即 i, j 分别指向数组首元素、尾元素+1
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i, j = 0, len(nums)
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# 循环，当搜索区间为空时跳出（当 i = j 时为空）
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while i < j:
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m = (i + j) // 2 # 计算中点索引 m
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if nums[m] < target: # 此情况说明 target 在区间 [m+1, j) 中
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i = m + 1
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elif nums[m] > target: # 此情况说明 target 在区间 [i, m) 中
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j = m
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else: # 找到目标元素，返回其索引
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return m
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return -1 # 未找到目标元素，返回 -1
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```
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=== "Go"
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@ -262,7 +287,7 @@ $$
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=== "Python"
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```py title=""
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# Python 中的数字理论上可以无限大（取决于内存）
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# Python 中的数字理论上可以无限大（取决于内存大小）
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# 因此无需考虑大数越界问题
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```
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@ -43,7 +43,11 @@ comments: true
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=== "Python"
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```python title="hashing_search.py"
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""" 哈希查找（数组） """
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def hashing_search(mapp, target):
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# 哈希表的 key: 目标元素，value: 索引
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# 若哈希表中无此 key ，返回 -1
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return mapp.get(target, -1)
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```
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=== "Go"
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@ -107,7 +111,11 @@ comments: true
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=== "Python"
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```python title="hashing_search.py"
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""" 哈希查找（链表） """
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def hashing_search1(mapp, target):
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# 哈希表的 key: 目标元素，value: 结点对象
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# 若哈希表中无此 key ，返回 -1
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return mapp.get(target, -1)
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```
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=== "Go"
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@ -47,7 +47,13 @@ comments: true
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=== "Python"
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```python title="linear_search.py"
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""" 线性查找（数组） """
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def linear_search(nums, target):
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# 遍历数组
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for i in range(len(nums)):
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if nums[i] == target: # 找到目标元素，返回其索引
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return i
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return -1 # 未找到目标元素，返回 -1
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```
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=== "Go"
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@ -119,7 +125,14 @@ comments: true
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=== "Python"
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```python title="linear_search.py"
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""" 线性查找（链表） """
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def linear_search1(head, target):
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# 遍历链表
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while head:
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if head.val == target: # 找到目标结点，返回之
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return head
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head = head.next
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return None # 未找到目标结点，返回 None
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```
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=== "Go"
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