Design Compressed String Iterator

Author: saurabhchris1

Design_Compressed_String_Iterator.py

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+# Design and implement a data structure for a compressed string iterator.
+# It should support the following operations: next and hasNext.
+#
+# The given compressed string will be in the form of each letter followed
+# by a positive integer representing the number of this letter existing in
+# the original uncompressed string.
+#
+# next() - if the original string still has uncompressed characters, return
+# the next letter; Otherwise return a white space.
+# hasNext() - Judge whether there is any letter needs to be uncompressed.
+#
+# Note:
+# Please remember to RESET your class variables declared in StringIterator,
+# as static/class variables are persisted across multiple test cases. Please see here for more details.
+#
+# Example:
+#
+# StringIterator iterator = new StringIterator("L1e2t1C1o1d1e1");
+#
+# iterator.next(); // return 'L'
+# iterator.next(); // return 'e'
+# iterator.next(); // return 'e'
+# iterator.next(); // return 't'
+# iterator.next(); // return 'C'
+# iterator.next(); // return 'o'
+# iterator.next(); // return 'd'
+# iterator.hasNext(); // return true
+# iterator.next(); // return 'e'
+# iterator.hasNext(); // return false
+# iterator.next(); // return ' '
+
+
+class StringIterator:
+
+    def __init__(self, compressedString):
+        self.s = compressedString
+        self.ptr = 0
+        self.num = 0
+        self.len = len(compressedString)
+        self.char = ""
+
+    def next(self):
+        if not self.hasNext():
+            return ' '
+        if self.num == 0:
+            self.char = self.s[self.ptr]
+            self.ptr = self.ptr + 1
+            arr = []
+            while self.ptr < self.len and self.s[self.ptr].isdigit():
+                arr.append(self.s[self.ptr])
+                self.ptr += 1
+            arr = "".join(arr)
+            self.num = int(arr) - 1
+            return self.char
+        else:
+            self.num -= 1
+            return self.char
+
+    def hasNext(self):
+        if self.ptr >= self.len and self.num == 0:
+            return False
+        return True
+
+# Your StringIterator object will be instantiated and called as such:
+# obj = StringIterator(compressedString)
+# param_1 = obj.next()
+# param_2 = obj.hasNext()