Merge pull request #31 from wiktorwojcik112/master

Add algorithms for binary to decimal and decimal to binary conversion

Author: carloshmartins

DIRECTORY.md

@@ -1,6 +1,9 @@
 # List of all files
 
 ## Algorithms
+  * conversion
+    * [Binary to decimal](https://github.com/TheAlgorithms/Swift/blob/master/algorithms/conversion/binary-to-decimal.swift)
+    * [Decimal to binary](https://github.com/TheAlgorithms/Swift/blob/master/algorithms/conversion/decimal-to-binary.swift)
   * Ai
     * Minimax
       * Sources

algorithms/conversion/binary-to-decimal.swift

@@ -0,0 +1,23 @@
+import Foundation
+
+/// This function accepts a binary number as String and converts it to decimal as Int. 
+/// If it's not valid binary number (a.k.a not made only from digits), it returns nil.
+public func convertBinaryToDecimal(binary: String) -> Int? {
+    if let _ = Int(binary) {
+        var decimal = 0
+
+        let digits = binary.map { Int(String($0))! }.reversed()
+        print(digits)
+        var power = 1
+
+        for digit in digits {
+            decimal += digit * power
+
+            power *= 2
+        }
+
+        return decimal
+    }
+
+    return nil
+}

algorithms/conversion/decimal-to-binary.swift

@@ -0,0 +1,12 @@
+/// This function accepts a non-negative number and returns its binary form as String.
+public func convertDecimalToBinary(decimal: Int) -> String {
+    var binary = ""
+    var decimal = decimal
+
+    while decimal != 0 {
+        binary.insert(decimal % 2 == 0 ? "0" : "1", at: binary.startIndex)
+        decimal /= 2
+    }
+
+    return binary
+}