Python实现二分查找、二叉树

二分查找

# def binary_search(alist,item):
#     n = len(alist)
#     mid = n//2
#     if n > 0:
#         if alist[mid] == item:
#             return True
#         elif item<alist[mid]:
#             return binary_search(alist[:mid],item)
#         elif item > alist[mid]:
#             return binary_search(alist[mid+1:],item)
#         return False
#
# if __name__ =="__main__"    :
#     li = [17, 20, 26, 31, 44, 54, 55, 77, 93]
#     print(binary_search(li,55))

二叉树

class Node(object):
    def __init__(self,item):
        self.elem = item
        self.lchild = None
        self.rchild = None

class Tree(object):
    def __init__(self):
        self.root = None
    def add(self,item):
        node = Node(item)
        if self.root is None:
            self.root = node
            return
        queue = [self.root]
        while queue:
            cur_node = queue.pop(0)
            if cur_node.lchild is None:
                cur_node.lchild = node
                return
            else:
                queue.append(cur_node.lchild)
            if cur_node.rchild is None:
                cur_node.rchild = node
            else:
                queue.append(cur_node.rchild)