#Leet Code# Binary Tree Max[待精简]

描述：递归调用，getMax返回 [节点值，经过节点左子节点的最大值，经过节点右节点的最大值]，每次递归同时查看是否存在不经过节点的值大于max。

代码：待优化

  1     def getLargeNode(self, a, b):
  2         if a and b:
  3             return max(a, b)
  4         elif a and not b:
  5             return a 
  6         elif not a and b:
  7             return b
  8         else:
  9             tmp = None
 10 
 11     def getMax(self, node):
 12         if node is None:
 13             return [None, None, None]
 14 
 15         left = self.getMax(node.left)
 16         right = self.getMax(node.right)
 17 
 18         pass_node_max = node.val
 19         if left[0] is not None:
 20             if left[1] > self.maxPath:
 21                 self.maxPath = item
 22             if left[2] > self.maxPath:
 23                 self.maxPath = item
 24 
 25             tmp = self.getLargeNode(left[1], left[2])
 26 
 27             if tmp is not None:
 28                 if tmp <= 0 and left[0] <= 0:
 29                     left_val = left[0]
 30                 elif tmp > 0 and left[0] <= 0:
 31                     left_val = left[0] + tmp
 32                     if tmp + left[0] > 0:
 33                         pass_node_max += left_val
 34                 elif tmp <= 0 and left[0] > 0:
 35                     left_val = left[0]
 36                     pass_node_max += left_val
 37                 else:
 38                     left_val = left[0] + tmp
 39                     pass_node_max += left_val
 40             else:
 41                 left_val = left[0]
 42                 if left[0] > 0:
 43                     pass_node_max += left[0]
 44         else:
 45             left_val = None
 46         
 47         if right[0] is not None:
 48             if right[1] > self.maxPath:
 49                 self.maxPath = right[1]
 50             if right[2] > self.maxPath:
 51                 self.maxPath = right[1]
 52 
 53             tmp = self.getLargeNode(right[1], right[2])
 54 
 55             if tmp is not None:
 56                 if tmp <= 0 and right[0] <= 0:
 57                     right_val = right[0]
 58                 elif tmp > 0 and right[0] <= 0:
 59                     right_val = right[0] + tmp
 60                     if tmp + right[0] > 0:
 61                         pass_node_max += right_val
 62                 elif tmp <= 0 and right[0] > 0:
 63                     right_val = right[0]
 64                     pass_node_max += right_val
 65                 else:
 66                     right_val = right[0] + tmp
 67                     pass_node_max += right_val
 68             else:
 69                 right_val = right[0]
 70                 if right[0] > 0:
 71                     pass_node_max += right[0]
 72         else:
 73             right_val = None
 74 
 75         if pass_node_max > self.maxPath:
 76             self.maxPath = pass_node_max
 77 
 78         return [node.val, left_val, right_val]
 79 
 80     def maxPathSum(self, root):
 81         self.maxPath = root.val
 82         if not(root.left or root.right):
 83             return self.maxPath
 84 
 85         result = self.getMax(root)
 86 
 87         root_val = root.val
 88         if result[1] > 0:
 89             root_val += result[1] 
 90         if result[2] > 0:
 91             root_val += result[2] 
 92         if root_val > self.maxPath:
 93             self.maxPath = root_val
 94         
 95         if result[1] > self.maxPath:
 96             self.maxPath = result[1]
 97         if result[2] > self.maxPath:
 98             self.maxPath = result[2]
 99 
100         return self.maxPath
posted @ 2014-07-16 18:42  mess4u  阅读(95)  评论(0)  编辑  收藏  举报