441. Arranging Coins

Author: Partho Biswas

README.md

@@ -384,6 +384,7 @@ I have solved quite a number of problems from several topics. See the below tabl
 |31| **[1231. Divide Chocolate](https://tinyurl.com/rduxzj3)** | [Python](https://tinyurl.com/wu6rdaw/1231_Divide_Chocolate.py), [Swift](https://tinyurl.com/wuja3c4/1231_Divide_Chocolate.swift) | [Art 1](https://tinyurl.com/sl7w7cb), [Art 2](https://tinyurl.com/w9wbcyl), [Art 3](https://tinyurl.com/te6wq5e) | Hard | I loved this problem. Very important |
 |32| **[1268. Search Suggestions System](https://tinyurl.com/ybwcd5nx)** | [Python](https://tinyurl.com/wu6rdaw/1268_Search_Suggestions_System.py), [Swift](https://tinyurl.com/wuja3c4/1268_Search_Suggestions_System.swift) | [Art 1](https://tinyurl.com/yac3kvrp), [Art 2](https://tinyurl.com/y9u3g66q), [Art 3](https://tinyurl.com/yc2u3mrx) | Medium | I loved this problem. Very versatile, ca be solved in a lot of different ways |
 |33| **[540. Single Element in a Sorted Array](https://tinyurl.com/y78xdorh)** | [Python](https://tinyurl.com/wu6rdaw/540_Single_Element_in_a_Sorted_Array.py), [Swift](https://tinyurl.com/wuja3c4/1268_Search_Suggestions_System.swift) |  | Medium | --- |
+|34| **[441. Arranging Coins](https://tinyurl.com/yaj6labj)** | [Python](https://tinyurl.com/wu6rdaw/441_Arranging_Coins.py), [Swift](https://tinyurl.com/wuja3c4/441_Arranging_Coins.swift) |  | Easy | --- |
 
 
 </p>

leetcode.com/swift/DS_ALGO_PRAC.playground/Sources/swift/441_Arranging_Coins.swift

@@ -0,0 +1,57 @@
+import Foundation
+
+// Brute force solution. Time Limit Exceeded
+class Solution {
+    func arrangeCoins(_ n: Int) -> Int {
+        if n == 0 {
+            return 0
+        }
+        
+        var (coins, steps) = (0, 0)
+        for i in 1...n {
+            coins += i
+            if coins <= n {
+                steps += 1
+            }
+        }
+        return steps
+    }
+}
+
+
+// Binary Search
+import Foundation
+class Solution {
+    func arrangeCoins(_ n: Int) -> Int {
+        var (left, right) = (0, n)
+        while left <= right {
+            var mid: Int = (left + right)/2
+            var requiredCoing = (mid*(mid + 1)) / 2
+            if requiredCoing == n {
+                return mid
+            }
+            if requiredCoing > n {
+                right = mid - 1
+            } else {
+                left = mid + 1
+            }
+        }
+        return right
+    }
+}
+
+/*
+ logn
+ 
+ 1-1
+ 2-3
+ 3-6
+ 4-10
+ 5-15
+ 6-21
+ 7-28
+ 8-36
+ 9-45
+ 1+2+3+4+5+6 = k(k+1)/2
+ 
+*/