Lecture03

lecture03/src/main/kotlin/io/rybalkinsd/kotlinbootcamp/practice/encoding.kt

@@ -1,41 +1,56 @@
-package io.rybalkinsd.kotlinbootcamp.practice
-
-/**
- * NATO phonetic alphabet
- */
-val alphabet = setOf("Alfa", "Bravo", "Charlie", "Delta", "Echo", "Foxtrot", "Golf", "Hotel", "India", "Juliett", "Kilo", "Lima", "Mike", "November", "Oscar", "Papa", "Quebec", "Romeo", "Sierra", "Tango", "Uniform", "Victor", "Whiskey", "Xray", "Yankee", "Zulu")
-
-/**
- * A mapping for english characters to phonetic alphabet.
- * [ a -> Alfa, b -> Bravo, ...]
- */
-val association: Map<Char, String> = TODO()
-
-/**
- * Extension function for String which encode it according to `association` mapping
- *
- * @return encoded string
- *
- * Example:
- * "abc".encode() == "AlfaBravoCharlie"
- *
- */
-fun String.encode(): String = TODO()
-
-/**
- * A reversed mapping for association
- * [ alpha -> a, bravo -> b, ...]
- */
-val reversedAssociation: Map<String, Char> = TODO()
-
-/**
- * Extension function for String which decode it according to `reversedAssociation` mapping
- *
- * @return encoded string or null if it is impossible to decode
- *
- * Example:
- * "alphabravocharlie".decode() == "abc"
- * "charliee".decode() == null
- *
- */
-fun String.decode(): String? = TODO()
+package io.rybalkinsd.kotlinbootcamp.practice
+/**
+ * NATO phonetic alphabet
+ */
+val alphabet = setOf("Alfa", "Bravo", "Charlie", "Delta", "Echo", "Foxtrot", "Golf", "Hotel", "India", "Juliett", "Kilo", "Lima", "Mike", "November", "Oscar", "Papa", "Quebec", "Romeo", "Sierra", "Tango", "Uniform", "Victor", "Whiskey", "Xray", "Yankee", "Zulu")
+/**
+ * A mapping for english characters to phonetic alphabet.
+ * [ a -> Alfa, b -> Bravo, ...]
+ */
+val association: Map<Char, String> = alphabet.associate { it[0].toLowerCase() to it }
+/**
+ * Extension function for String which encode it according to `association` mapping
+ *
+ * @return encoded string
+ *
+ * Example:
+ * "abc".encode() == "AlfaBravoCharlie"
+ *
+ */
+fun String.encode(): String = map { it.toLowerCase() }.map { association[it] ?: it }.joinToString("")
+/**
+ * A reversed mapping for association
+ * [ alpha -> a, bravo -> b, ...]
+ */
+val reversedAssociation: Map<String, Char> = alphabet.associate { it to it[0] }
+/**
+ * Extension function for String which decode it according to `reversedAssociation` mapping
+ *
+ * @return encoded string or null if it is impossible to decode
+ *
+ * Example:
+ * "alphabravocharlie".encode() == "abc"
+ * "charliee".decode() == null
+ *
+ */
+fun String.decode(): String? {
+    var res = ""
+    var input = this
+    var word = ""
+    for (letter in input) {
+        if (letter in '0'..'9' || letter == ' ') {
+            res += letter
+            continue
+        }
+        word += letter
+        if (reversedAssociation[word] != null) {
+            res += (reversedAssociation[word])
+            res = res.toLowerCase()
+            word = ""
+        }
+    }
+    when (word) {
+        "" -> return res
+        else -> return null
+    }
+}