re.makeTree("e", None, None)
rf.makeTree("f", None, None)
r1, r2, r3, r4, r = Tree(), Tree(), Tree(), Tree(), Tree()
r1.makeTree("-", rc, rd)
r2.makeTree("*", rb, r1)
r3.makeTree("+", ra, r2)
r4.makeTree("/", re, rf)
r.makeTree("-", r3, r4)
r.preOrder(r)
r.inOrder(r)
r.postOrder(r)
r.levelOrder(r)
print r.leaves_count(r)
大学的时候学过kmp算法，最近在看的时候发现竟然忘了，所以去重新看了看书，然后用python写下了这个算法：
def kmp(text, pattern):
"""kmp算法 """
pattern = list(pattern)
next = [-1] * len(pattern)
#next 函数
i, j = 1, -1
for i in range(1, len(pattern)):
j = next[i - 1]
while True:
if pattern[i - 1] == pattern[j] or j == -1:
next[i] = j + 1
break
else:
j = next[j]
#循环比较
i, j = 0, 0
while i < len(text) and j < len(pattern):
if text[i] == pattern[j] or j == -1:
i += 1
j += 1
else:
j = next[j]
#返回结果 如果匹配，返回匹配的位置，否则返回-1
if j == len(pattern):
print i – j
else:
print -1
