adding udpates

src/my_project/interviews/top_150_questions_round_23/ex_12_insert_delete_get_random.py

@@ -0,0 +1,71 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+import random
+
+
+class RandomizedSet:
+
+    def __init__(self):
+        self.data_map = {} # dictionary, aka map, aka hashtable, aka hashmap
+        self.data = [] # list aka array
+
+    def insert(self, val: int) -> bool:
+
+        # the problem indicates we need to return False if the item 
+        # is already in the RandomizedSet---checking if it's in the
+        # dictionary is on average O(1) where as
+        # checking the array is on average O(n)
+        if val in self.data_map:
+            return False
+
+        # add the element to the dictionary. Setting the value as the 
+        # length of the list will accurately point to the index of the 
+        # new element. (len(some_list) is equal to the index of the last item +1)
+        self.data_map[val] = len(self.data)
+
+        # add to the list
+        self.data.append(val)
+
+        return True
+
+    def remove(self, val: int) -> bool:
+
+        # again, if the item is not in the data_map, return False. 
+        # we check the dictionary instead of the list due to lookup complexity
+        if not val in self.data_map:
+            return False
+
+        # essentially, we're going to move the last element in the list 
+        # into the location of the element we want to remove. 
+        # this is a significantly more efficient operation than the obvious 
+        # solution of removing the item and shifting the values of every item 
+        # in the dicitionary to match their new position in the list
+        last_elem_in_list = self.data[-1]
+        index_of_elem_to_remove = self.data_map[val]
+
+        self.data_map[last_elem_in_list] = index_of_elem_to_remove
+        self.data[index_of_elem_to_remove] = last_elem_in_list
+
+        # change the last element in the list to now be the value of the element 
+        # we want to remove
+        self.data[-1] = val
+
+        # remove the last element in the list
+        self.data.pop()
+
+        # remove the element to be removed from the dictionary
+        self.data_map.pop(val)
+        return True
+
+    def getRandom(self) -> int:
+        # if running outside of leetcode, you need to `import random`.
+        # random.choice will randomly select an element from the list of data.
+        return random.choice(self.data)
+
+
+
+# Your RandomizedSet object will be instantiated and called as such:
+# obj = RandomizedSet()
+# param_1 = obj.insert(val)
+# param_2 = obj.remove(val)
+# param_3 = obj.getRandom()

src/my_project/interviews_typescript/top_150_questions_round_23/ex_12_insert_delete_get_random.ts

@@ -0,0 +1,72 @@
+class RandomizedSet {
+    private dataMap: Map<number, number>; // dictionary, aka map, aka hashtable, aka hashmap
+    private data: number[]; // list aka array
+
+    constructor() {
+        this.dataMap = new Map();
+        this.data = [];
+    }
+
+    insert(val: number): boolean {
+        // the problem indicates we need to return False if the item 
+        // is already in the RandomizedSet---checking if it's in the
+        // dictionary is on average O(1) where as
+        // checking the array is on average O(n)
+        if (this.dataMap.has(val)) {
+            return false;
+        }
+
+        // add the element to the dictionary. Setting the value as the 
+        // length of the list will accurately point to the index of the 
+        // new element. (len(some_list) is equal to the index of the last item +1)
+        this.dataMap.set(val, this.data.length);
+
+        // add to the list
+        this.data.push(val);
+
+        return true;
+    }
+
+    remove(val: number): boolean {
+        // again, if the item is not in the dataMap, return false. 
+        // we check the dictionary instead of the list due to lookup complexity
+        if (!this.dataMap.has(val)) {
+            return false;
+        }
+
+        // essentially, we're going to move the last element in the list 
+        // into the location of the element we want to remove. 
+        // this is a significantly more efficient operation than the obvious 
+        // solution of removing the item and shifting the values of every item 
+        // in the dictionary to match their new position in the list
+        const lastElemInList = this.data[this.data.length - 1];
+        const indexOfElemToRemove = this.dataMap.get(val)!;
+
+        this.dataMap.set(lastElemInList, indexOfElemToRemove);
+        this.data[indexOfElemToRemove] = lastElemInList;
+
+        // change the last element in the list to now be the value of the element 
+        // we want to remove
+        this.data[this.data.length - 1] = val;
+
+        // remove the last element in the list
+        this.data.pop();
+
+        // remove the element to be removed from the dictionary
+        this.dataMap.delete(val);
+        return true;
+    }
+
+    getRandom(): number {
+        // random.choice will randomly select an element from the list of data.
+        return this.data[Math.floor(Math.random() * this.data.length)];
+    }
+}
+
+/**
+ * Your RandomizedSet object will be instantiated and called as such:
+ * var obj = new RandomizedSet()
+ * var param_1 = obj.insert(val)
+ * var param_2 = obj.remove(val)
+ * var param_3 = obj.getRandom()
+ */

tests/test_150_questions_round_22/test_12_insert_delete_get_random_round_22.py

@@ -0,0 +1,35 @@
+import unittest
+from src.my_project.interviews.top_150_questions_round_22\
+.ex_12_insert_delete_get_random import RandomizedSet
+
+class InsertAndDeleteGetRandomTestCase(unittest.TestCase):
+
+    def test_first_case(self):
+        randomized_set = RandomizedSet()
+        self.assertTrue(randomized_set.insert(1))   # Inserts 1, returns true
+        self.assertFalse(randomized_set.remove(2))  # 2 not present, returns false
+        self.assertTrue(randomized_set.insert(2))   # Inserts 2, returns true
+        self.assertIn(randomized_set.getRandom(), [1, 2])  # getRandom returns 1 or 2
+        self.assertTrue(randomized_set.remove(1))   # Removes 1, returns true
+        self.assertFalse(randomized_set.insert(2))  # 2 already present, returns false
+        self.assertEqual(randomized_set.getRandom(), 2)    # Only 2 in set
+
+    def test_insert_duplicate(self):
+        randomized_set = RandomizedSet()
+        self.assertTrue(randomized_set.insert(5))
+        self.assertFalse(randomized_set.insert(5))  # duplicate
+
+    def test_remove_nonexistent(self):
+        randomized_set = RandomizedSet()
+        self.assertFalse(randomized_set.remove(99))
+
+    def test_remove_existing(self):
+        randomized_set = RandomizedSet()
+        randomized_set.insert(10)
+        self.assertTrue(randomized_set.remove(10))
+        self.assertFalse(randomized_set.remove(10))  # already removed
+
+    def test_get_random_single_element(self):
+        randomized_set = RandomizedSet()
+        randomized_set.insert(42)
+        self.assertEqual(randomized_set.getRandom(), 42)

tests/test_150_questions_round_23/test_12_insert_delete_get_random_round_23.py

@@ -0,0 +1,35 @@
+import unittest
+from src.my_project.interviews.top_150_questions_round_23\
+.ex_12_insert_delete_get_random import RandomizedSet
+
+class InsertAndDeleteGetRandomTestCase(unittest.TestCase):
+
+    def test_first_case(self):
+        randomized_set = RandomizedSet()
+        self.assertTrue(randomized_set.insert(1))   # Inserts 1, returns true
+        self.assertFalse(randomized_set.remove(2))  # 2 not present, returns false
+        self.assertTrue(randomized_set.insert(2))   # Inserts 2, returns true
+        self.assertIn(randomized_set.getRandom(), [1, 2])  # getRandom returns 1 or 2
+        self.assertTrue(randomized_set.remove(1))   # Removes 1, returns true
+        self.assertFalse(randomized_set.insert(2))  # 2 already present, returns false
+        self.assertEqual(randomized_set.getRandom(), 2)    # Only 2 in set
+
+    def test_insert_duplicate(self):
+        randomized_set = RandomizedSet()
+        self.assertTrue(randomized_set.insert(5))
+        self.assertFalse(randomized_set.insert(5))  # duplicate
+
+    def test_remove_nonexistent(self):
+        randomized_set = RandomizedSet()
+        self.assertFalse(randomized_set.remove(99))
+
+    def test_remove_existing(self):
+        randomized_set = RandomizedSet()
+        randomized_set.insert(10)
+        self.assertTrue(randomized_set.remove(10))
+        self.assertFalse(randomized_set.remove(10))  # already removed
+
+    def test_get_random_single_element(self):
+        randomized_set = RandomizedSet()
+        randomized_set.insert(42)
+        self.assertEqual(randomized_set.getRandom(), 42)