finished

src/main/java/io/zipcoder/Problem1.java

@@ -1,4 +1,49 @@
 package io.zipcoder;
 
+import java.util.HashMap;
+
 public class Problem1 {
+
+    private HashMap<Character, Character> replaceChars = new HashMap<Character, Character>();
+
+    public Problem1() {
+        replaceChars.put('f', '7');
+        replaceChars.put('s', '$');
+        replaceChars.put('1', '!');
+        replaceChars.put('a', '@');
+    }
+
+    public String replaceCharsByIteration(String input) {
+        char[] allChars = input.toCharArray();
+        for(int i = 0; i < allChars.length; i++) {
+            char c = allChars[i];
+            if(replaceChars.containsKey(Character.toLowerCase(c))) {
+                allChars[i] = replaceChars.get(Character.toLowerCase(c));
+            }
+        }
+
+        return new String(allChars);
+    }
+
+    public String replaceCharsByRecursion(String input) {
+        char[] allChars = input.toCharArray();
+        for(char c : replaceChars.keySet()) {
+            int index = input.indexOf(Character.toLowerCase(c));
+            if(index > -1) {
+                allChars[index] = replaceChars.get(c);
+                input = new String(allChars);
+                replaceCharsByRecursion(input);
+            }
+            else {
+                index = input.indexOf(Character.toUpperCase(c));
+                if(index > -1) {
+                    allChars[index] = replaceChars.get(c);
+                    input = new String(allChars);
+                    replaceCharsByRecursion(input);
+                }
+            }
+        }
+        return input;
+    }
+
 }

src/test/java/io/zipcoder/Problem1Test.java

@@ -1,4 +1,27 @@
 package io.zipcoder;
 
+import org.junit.Assert;
+import org.junit.Test;
+
 public class Problem1Test {
+
+    @Test
+    public void replaceCharsByIterationTest() {
+        Problem1 problem1 = new Problem1();
+        String input = "The Farmer went to the store to get 1 dollar’s worth of fertilizer";
+
+        String expected = "The 7@rmer went to the $tore to get ! doll@r’$ worth o7 7ertilizer";
+        String actual = problem1.replaceCharsByIteration(input);
+        Assert.assertEquals(expected, actual);
+    }
+
+    @Test
+    public void replaceCharsByRecursionTest() {
+        Problem1 problem1 = new Problem1();
+        String input = "The Farmer went to the store to get 1 dollar’s worth of fertilizer";
+
+        String expected = "The 7@rmer went to the $tore to get ! doll@r’$ worth o7 7ertilizer";
+        String actual = problem1.replaceCharsByRecursion(input);
+        Assert.assertEquals(expected, actual);
+    }
 }