add insert-delete-getrandom-o1-duplicates-allowed.py

Author: lightmen

python/hash-table/insert-delete-getrandom-o1-duplicates-allowed.py

@@ -0,0 +1,51 @@
+class RandomizedCollection(object):
+
+    def __init__(self):
+        """
+        Initialize your data structure here.
+        """
+        self.d = collections.defaultdict(set)
+        self.l = []
+
+    def insert(self, val):
+        """
+        Inserts a value to the collection. Returns true if the collection did not already contain the specified element.
+        :type val: int
+        :rtype: bool
+        """
+        bool_ret = val not in self.l
+        self.d[val].add(len(self.l))
+        self.l.append(val)
+        return bool_ret
+
+    def remove(self, val):
+        """
+        Removes a value from the collection. Returns true if the collection contained the specified element.
+        :type val: int
+        :rtype: bool
+        """
+        if val not in self.l:
+            return False
+        last_val = self.l.pop()
+        self.d[last_val].remove(len(self.l))
+        if val != last_val:
+            index = self.d[val].pop()
+            self.l[index] = last_val
+            self.d[last_val].add(index)
+
+        if not self.d[val]:
+            del self.d[val]
+        return True
+
+    def getRandom(self):
+        """
+        Get a random element from the collection.
+        :rtype: int
+        """
+        return self.l[random.randint(0, len(self.l) - 1)]
+
+# Your RandomizedCollection object will be instantiated and called as such:
+# obj = RandomizedCollection()
+# param_1 = obj.insert(val)
+# param_2 = obj.remove(val)
+# param_3 = obj.getRandom()

python/hash-table/sort-characters-by-frequency[1].py

@@ -0,0 +1,7 @@
+class Solution(object):
+    def frequencySort(self, s):
+        """
+        :type s: str
+        :rtype: str
+        """
+        return ''.join(c * t for c, t in collections.Counter(s).most_common())