Mini Parser

Author: anantkaushik

385-mini-parser.py

@@ -0,0 +1,91 @@
+"""
+Problem Link: https://leetcode.com/problems/mini-parser/
+
+Given a nested list of integers represented as a string, implement a parser to deserialize it.
+Each element is either an integer, or a list -- whose elements may also be integers or other lists.
+
+Note: You may assume that the string is well-formed:
+String is non-empty.
+String does not contain white spaces.
+String contains only digits 0-9, [, - ,, ].
+ 
+Example 1:
+Given s = "324",
+You should return a NestedInteger object which contains a single integer 324.
+ 
+Example 2:
+Given s = "[123,[456,[789]]]",
+Return a NestedInteger object containing a nested list with 2 elements:
+1. An integer containing value 123.
+2. A nested list containing two elements:
+    i.  An integer containing value 456.
+    ii. A nested list with one element:
+         a. An integer containing value 789.
+"""
+# """
+# This is the interface that allows for creating nested lists.
+# You should not implement it, or speculate about its implementation
+# """
+#class NestedInteger:
+#    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:
+    def deserialize(self, s: str) -> NestedInteger:
+      stack, num, last = [], "", None
+      for c in s:
+        if c.isdigit() or c == "-": 
+          num += c
+
+        elif c == "," and num:
+            stack[-1].add(NestedInteger(int(num)))
+            num = ""
+
+        elif c == "[":
+            elem = NestedInteger()
+            if stack:
+              stack[-1].add(elem)
+            stack.append(elem)
+
+        elif c == "]":
+            if num:
+                stack[-1].add(NestedInteger(int(num)))
+                num = ""
+            last = stack.pop()
+              
+      return last if last else NestedInteger(int(num))