mini-parser.py

# V0 

# V1 
# http://bookshadow.com/weblog/2016/08/15/leetcode-mini-parser/
class Solution(object):
    def deserialize(self, s):
        """
        :type s: str
        :rtype: NestedInteger
        """
        stack = []
        sigma, negmul = None, 1
        for c in s:
            if c == '-':
                negmul = -1
            elif '0' <= c <= '9':
                sigma = (sigma or 0) * 10 + int(c)
            elif c == '[':
                stack.append(NestedInteger())
            else:
                if sigma is not None:
                    stack[-1].add(NestedInteger(sigma * negmul))
                    sigma, negmul = None, 1
                if c == ']':
                    top = stack.pop()
                    if stack: stack[-1].add(top)
                    else: return top
        return NestedInteger((sigma or 0) * negmul)

# V2 
# Time:  O(n)
# Space: O(h)
class NestedInteger(object):
   def __init__(self, value=None):
       """
       If value is not specified, initializes an empty list.
       Otherwise initializes a single integer equal to value.
       """

   def isInteger(self):
       """
       @return True if this NestedInteger holds a single integer, rather than a nested list.
       :rtype bool
       """

   def add(self, elem):
       """
       Set this NestedInteger to hold a nested list and adds a nested integer elem to it.
       :rtype void
       """

   def setInteger(self, value):
       """
       Set this NestedInteger to hold a single integer equal to value.
       :rtype void
       """

   def getInteger(self):
       """
       @return the single integer that this NestedInteger holds, if it holds a single integer
       Return None if this NestedInteger holds a nested list
       :rtype int
       """

   def getList(self):
       """
       @return the nested list that this NestedInteger holds, if it holds a nested list
       Return None if this NestedInteger holds a single integer
       :rtype List[NestedInteger]
       """


class Solution(object):
    def deserialize(self, s):
        if not s:
            return NestedInteger()

        if s[0] != '[':
            return NestedInteger(int(s))

        stk = []

        i = 0
        for j in xrange(len(s)):
            if s[j] == '[':
                stk += NestedInteger(),
                i = j+1
            elif s[j] in ',]':
                if s[j-1].isdigit():
                    stk[-1].add(NestedInteger(int(s[i:j])))
                if s[j] == ']' and len(stk) > 1:
                    cur = stk[-1]
                    stk.pop()
                    stk[-1].add(cur)
                i = j+1

        return stk[-1]