Crossopt 1

crossopt/assignment1/Q1.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+# coding: utf-8
+from re import split
+from collections import Counter
+
+
+# return hashable count of elements
+def hashCount(container):
+    return tuple(sorted(Counter(container).items()))
+
+
+# checks whether strings are anagrams
+def isStringAnagram(str1, str2, case_sensitive=False):
+    if not case_sensitive:
+        str1 = str1.lower()
+        str2 = str2.lower()
+
+    return Counter(str1) == Counter(str2)
+
+
+# checks whether sentences are anagrams. Punctuation is ignored
+def isSentenceAnagram(str1, str2, case_sensitive=False):
+    if not case_sensitive:
+        str1 = str1.lower()
+        str2 = str2.lower()
+
+    # TODO - figure out apostrophes
+    # get list of words, replace all words with their count, make it hashable
+    words1 = [hashCount(word) for word in split('\W', str1) if word]
+    words2 = [hashCount(word) for word in split('\W', str2) if word]
+    return Counter(words1) == Counter(words2)
+
+
+if __name__ == "__main__":
+    str1 = "triangle"
+    str2 = "Integral"
+    assert not isStringAnagram(str1, str2, 1)
+    assert isStringAnagram(str1, str2)
+
+    str1 = "посеять: клоповник"
+    str2 = "полковник опьется"
+    assert isSentenceAnagram(str1, str2, 1)
+    assert isSentenceAnagram(str1, str2, 0)

crossopt/assignment1/Q2.py

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+#!/usr/bin/env python3
+
+
+class Node(object):
+    def __init__(self, data):
+        self.data = data
+        self.next = None
+
+
+class LinkedList(object):
+    def __init__(self):
+        self.head = None
+
+    # adds element to front of list
+    def insert(self, new_elem):
+        new_node = Node(new_elem)
+        new_node.next = self.head
+        self.head = new_node
+
+    def __len__(self):
+        ans = 0
+        cnt = self.head
+        while cnt:
+            ans += 1
+            cnt = cnt.next
+        return ans
+
+    def __str__(self):
+        ans = []
+        cnt = self.head
+        while cnt:
+            ans.append(str(cnt.data))
+            cnt = cnt.next
+        return "{" + ", ".join(ans) + "}"
+
+    # list[-k] returns kth element from end of list, last element is -1
+    def __getitem__(self, k):
+        length = len(self)
+
+        if k >= 0:
+            raise NotImplementedError()
+        elif k < -length:
+            raise IndexError()
+
+        cnt = self.head
+        for i in range(length + k):
+            cnt = cnt.next
+        return cnt
+
+if __name__ == "__main__":
+    list = LinkedList()
+    list.insert(5)
+    list.insert('dog')
+    list.insert(set([1, 2, 3]))
+    print("list is {}".format(list))
+    for k in range(1, 4):
+        print("for k = {}, kth from last element is {}"
+              .format(k, list[-k].data))