:type nums: List[int]
:rtype: TreeNode
"""
if not nums:
return None
return self.buildBST(nums,0,len(nums)-1)
def buildBST(self,nums,i,j):
if i> j :
return None
if i == j:
no = TreeNode(nums[i])
return no
mid = (i+j)//2
root = TreeNode(nums[mid])
left = self.buildBST(nums,i,mid-1)
right = self.buildBST(nums,mid+1,j)
root.left = left
root.right = right
return root
if __name__ == '__main__':
so = Solution()
root = so.sortedArrayToBST([1,2,3,4,5,6,7])
TreeNode.inOrderRec(root)
print()
TreeNode.preOrder(root)
t = TreeNode(begin)
ans.append(t)
return ans
if begin + 1 == end:
t1 = TreeNode(begin)
t1.right = TreeNode(end)
ans.append(t1)
t2 = TreeNode(end)
t2.left = TreeNode(begin)
ans.append(t2)
return ans
for i in range(begin, end + 1):
leftTreeSet = self.dfs(begin, i - 1)
rightTreeSet = self.dfs(i + 1, end)
for nodeL in leftTreeSet:
for nodeR in rightTreeSet:
ro = TreeNode(i)
ro.left = nodeL
ro.right = nodeR
ans.append(ro)
return ans
if __name__ == '__main__':
so = Solution()
ans = so.generateTrees(2)
for n in ans:
TreeNode.preOrder(n)
print()
return ans
if begin +1 == end:
t1 = TreeNode(begin)
t1.right = TreeNode(end)
ans.append(t1)
t2 = TreeNode(end)
t2.left = TreeNode(begin)
ans.append(t2)
return ans
for i in range(begin,end+1):
leftTreeSet = self.dfs(begin,i-1)
rightTreeSet = self.dfs(i+1,end)
for nodeL in leftTreeSet:
for nodeR in rightTreeSet:
ro = TreeNode(i)
ro.left = nodeL
ro.right = nodeR
ans.append(ro)
return ans
if __name__ == '__main__':
so = Solution()
ans = so.generateTrees(2)
for n in ans:
TreeNode.preOrder(n)
print()
