二叉树问题---打印二叉树的边界节点

1.头节点为边界节点
2.叶节点为边界节点
3.如果节点在其所在层中的最左边或最右边，那么也是边界节点

1.头节点为边界节点
2.叶节点为边界节点
3.树左边界延伸下去的路径为边界节点
4.树右边界延伸下去的路径为边界节点

#标准一
def printEdge1(root):
def getHeight(root, height=0):
if not root:
return 0
return max(getHeight(root.left, height+1), getHeight(root.right, height+1)) + 1

def getMap(root, i, map):
if not root:
return
if map[i][0] == None:
map[i][0] = root
map[i][1] = root
getMap(root.left, i+1, map)
getMap(root.right, i+1, map)

def printLeafNotInMap(root, i, map):
if not root:
return
if not root.left and not root.right and root != map[i][0] and \
root != map[i][1]:
print(root.val, end=' ')
printLeafNotInMap(root.left, i+1, map)
printLeafNotInMap(root.right, i+1, map)

if not root:
return
height = getHeight(root)
map = [[None for i in range(2)] for j in range(height)]
getMap(root, 0, map)
for i in range(len(map)):
print(map[i][0].val, end=' ')
printLeafNotInMap(root, 0, map)
for i in range(len(map)-1, -1, -1):
if map[i][0] != map[i][1]:
print(map[i][1].val, end=' ')

#标准二
def printEdge2(root):
def printLeft(root, isPrint):
if not root:
return
if isPrint or (root.left == None and root.right == None):
print(root.val, end=' ')
printLeft(root.left, isPrint)
printLeft(root.right, bool(isPrint and root.left == None))

def printRight(root, isPrint):
if not root:
return
printRight(root.left, bool(isPrint and root.right == None))
printRight(root.right, isPrint)
if isPrint or (root.left == None and root.right == None):
print(root.val, end=' ')

if not root:
return
print(root.val, end=' ')
if root.left and root.right:
printLeft(root.left, True)
printRight(root.right, True)
elif root.left:
printEdge2(root.left)
elif root.right:
printEdge2(root.right)