【二叉树】二叉树的非递归遍历

1 class G:
2     def evaluate(self, l, r, v):
3         self.left = l
4         self.right =r
5         self.val = v

 1 tree = [G() for i in xrange(9)]
 2 tree[8].evaluate(None, None, 8)
 3 tree[7].evaluate(None, None, 7)
 4 tree[6].evaluate(None, None, 6)
 5 tree[5].evaluate(None, None, 5)
 6 tree[4].evaluate(tree[7], tree[8], 4)
 7 tree[3].evaluate(None, None, 3)
 8 tree[2].evaluate(tree[5], tree[6], 2)
 9 tree[1].evaluate(tree[3], tree[4], 1)
10 tree[0].evaluate(tree[1], tree[2], 0)

 1 def preOrder(t): 
 2     p = t
 3     stack = []
 4     rslt = []
 5     while p or stack:
 6        if p:
 7           rslt.append(p.val)
 8           stack.append(p.right)
 9           p = p.left
10        else:
11           p = stack.pop()
12     print rslt

 1 def inOrder(t): 
 2     p = t
 3     stack = []
 4     rslt = []
 5     while p or stack:
 6         if p:
 7             stack.append(p)
 8             p = p.left
 9         else:
10             s = stack.pop()
11             rslt.append(s.val)
12             p = s.right
13     print rslt

 1  def postOrder(t):
 2          p = t
 3          leftStack = []
 4          rightStack = []
 5          rslt = []
 6          while (p or leftStack or rightStack):
 7              if p:
 8                  leftStack.append(p)
 9                  p = p.left
10              elif leftStack and rightStack and leftStack[-1] == rightStack[-1]:
11                  leftStack.pop().val
12                  rslt.append(rightStack.pop().val)
13              else:
14                  rightStack.append(leftStack[-1])
15                  p = leftStack[-1].right
16          print rslt