数组list1 = [1,2,3,4,5,6,7]
先找到中点，作为根节点，然后左边都比根节点小，右边都比根节点大
然后左右两边又同样找到根节点，利用递归，左节点都比根节点和右节点小，右节点都比左节点和根节点大
class TreeNode:
def __init__(self, val):
self.val = val
self.left, self.right = None, None
class Solution:
def listtotree(self, A):
if len(A) == 0:
return None
left, right = 0, len(A) - 1
return self.gettree(A, left, right)
# 递归
def gettree(self, A, left, right):
if left <= right:
mid = (left + right) // 2
root = TreeNode(A[mid])
root.left = self.gettree(A, left, mid - 1)
root.right = self.gettree(A, mid + 1, right)
else:
return None
return root
# 先序遍历
def view(self,root):
if root == None:
return
print root.val
self.view(root.left)
self.view(root.right)
if __name__ == '__main__':
list1 = [1,2,3,4,5,6,7]
tree = Solution()
data = tree.listtotree(list1)
print tree.view(data)