380. Insert Delete GetRandom O(1)

Author: Partho Biswas

README.md

@@ -156,6 +156,7 @@ I have solved quite a number of problems from several topics. See the below tabl
 |48| **[362. Design Hit Counter](https://tinyurl.com/sswrcc3)** | [Python](https://tinyurl.com/wu6rdaw/362_Design_Hit_Counter.py), [Swift](https://tinyurl.com/wuja3c4/362_Design_Hit_Counter.swift)| --- | Medium | --- |
 |49| **[289. Game of Life](https://tinyurl.com/y5ujyvu5)** | [Python](https://tinyurl.com/wu6rdaw/289_Game_of_Life.py), [Swift](https://tinyurl.com/wuja3c4/289_Game_of_Life.swift)| --- | Medium | --- |
 |50| **[54. Spiral Matrix](https://tinyurl.com/yy5rnvce)** | [Python](https://tinyurl.com/wu6rdaw/54_Spiral_Matrix.py), [Swift](https://tinyurl.com/wuja3c4/54_Spiral_Matrix.swift)| [Official](https://tinyurl.com/s6np53k) | Medium | --- |
+|51| **[380. Insert Delete GetRandom O(1)](https://tinyurl.com/y3urnkfj)** | [Python](https://tinyurl.com/wu6rdaw/380_Insert_Delete_GetRandom_O(1).py), [Swift](https://tinyurl.com/wuja3c4/380_Insert_Delete_GetRandom_O(1).swift)| [Official](https://tinyurl.com/t4t38od) | Medium | --- |
 
 
 </p>

leetcode.com/python/380_Insert_Delete_GetRandom_O(1).py

@@ -0,0 +1,50 @@
+import random
+class RandomizedSet(object):
+
+    def __init__(self):
+        """
+        Initialize your data structure here.
+        """
+        self.valueIdxMap = {}
+        self.valueList = []
+
+    def insert(self, val):
+        """
+        Inserts a value to the set. Returns true if the set did not already contain the specified element.
+        :type val: int
+        :rtype: bool
+        """
+        if val in self.valueIdxMap:
+            return False
+        self.valueIdxMap[val] = len(self.valueList)
+        self.valueList.append(val)
+        return True
+
+    def remove(self, val):
+        """
+        Removes a value from the set. Returns true if the set contained the specified element.
+        :type val: int
+        :rtype: bool
+        """
+        if val in self.valueIdxMap:
+            idx = self.valueIdxMap[val]
+            lastVal = self.valueList[-1]
+            self.valueList[idx] = lastVal
+            self.valueIdxMap[lastVal] = idx
+            self.valueList.pop()
+            del self.valueIdxMap[val]
+            return True
+        return False
+
+    def getRandom(self):
+        """
+        Get a random element from the set.
+        :rtype: int
+        """
+        return random.choice(self.valueList)
+
+# 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()

leetcode.com/swift/DS_ALGO_PRAC.playground/Sources/swift/380_Insert_Delete_GetRandom_O(1).swift

@@ -0,0 +1,50 @@
+import Foundation
+
+
+class RandomizedSet {
+    var valueIdxMap = [Int:Int]()
+    var valueList = [Int]()
+
+    /** Initialize your data structure here. */
+    init() {
+        
+    }
+    
+    /** Inserts a value to the set. Returns true if the set did not already contain the specified element. */
+    func insert(_ val: Int) -> Bool {
+        guard self.valueIdxMap[val] == nil else {
+            return false
+        }
+        self.valueIdxMap[val] = self.valueList.count
+        self.valueList.append(val)
+        return true
+    }
+    
+    /** Removes a value from the set. Returns true if the set contained the specified element. */
+    func remove(_ val: Int) -> Bool {
+        guard self.valueIdxMap[val] != nil else {
+            return false
+        }
+        let idx = self.valueIdxMap[val]
+        let lastVal = self.valueList.last
+        self.valueList[idx!] = lastVal!
+        self.valueIdxMap[lastVal!] = idx
+        self.valueList.popLast()
+        self.valueIdxMap.removeValue(forKey: val)
+        return true
+    }
+    
+    /** Get a random element from the set. */
+    func getRandom() -> Int {
+        var idx = Int.random(in: 0..<self.valueList.count)
+        return self.valueList[idx]
+    }
+}
+
+/**
+ * Your RandomizedSet object will be instantiated and called as such:
+ * let obj = RandomizedSet()
+ * let ret_1: Bool = obj.insert(val)
+ * let ret_2: Bool = obj.remove(val)
+ * let ret_3: Int = obj.getRandom()
+ */