diff --git a/src/main/java/io/zipcoder/Problem1.java b/src/main/java/io/zipcoder/Problem1.java
index 6cd6024..24d2a09 100644
--- a/src/main/java/io/zipcoder/Problem1.java
+++ b/src/main/java/io/zipcoder/Problem1.java
@@ -1,4 +1,64 @@
 package io.zipcoder;
 
+import java.util.HashMap;
+import java.util.Map;
+
 public class Problem1 {
+
+    private Map<Character, Character> map;
+
+    public Problem1() {
+        map = new HashMap<Character, Character>();
+        initializeMap();
+    }
+
+    public Map<Character, Character> getMap() {
+        return map;
+    }
+
+    public void initializeMap() {
+        map.put('f', '7');
+        map.put('s', '$');
+        map.put('1', '!');
+        map.put('a', '@');
+    }
+
+    public String replaceCharsWithIteration(String originalString) {
+        char[] charArray = originalString.toCharArray();
+        for (int i = 0; i < charArray.length; i++) {
+            char c = Character.toLowerCase(charArray[i]);
+            if (map.containsKey(c)) {
+                charArray[i] = map.get(c);
+            }
+        }
+        return new String(charArray);
+    }
+
+    public String replaceCharsWithRecursion(String originalString, int index) {
+        char[] charArray = originalString.toCharArray();
+        char c = Character.toLowerCase(charArray[index]);
+        if (map.containsKey(c)) {
+            charArray[index] = map.get(c);
+        }
+        if (index < originalString.length() - 1) {
+            index++;
+            return replaceCharsWithRecursion(new String(charArray), index);
+        }
+        return new String(charArray);
+    }
+
+    public static void main(String[] args) {
+        Problem1 problem1 = new Problem1();
+
+        String input = "The Farmer went to the store to get 1 dollar\'s worth of fertilizer";
+        String output = "The 7@rmer went to the $tore to get ! doll@r\'$ worth o7 7ertilizer";
+
+        String test = problem1.replaceCharsWithRecursion(input, 0);
+
+        System.out.println(input);
+        System.out.println(output);
+        System.out.println(test);
+    }
+
+
 }
diff --git a/src/test/java/io/zipcoder/Problem1Test.java b/src/test/java/io/zipcoder/Problem1Test.java
index de82e99..1e6518d 100644
--- a/src/test/java/io/zipcoder/Problem1Test.java
+++ b/src/test/java/io/zipcoder/Problem1Test.java
@@ -1,4 +1,51 @@
 package io.zipcoder;
 
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
 public class Problem1Test {
+
+    private Problem1 problem1;
+    private String input = "The Farmer went to the store to get 1 dollar\'s worth of fertilizer";
+    private String output = "The 7@rmer went to the $tore to get ! doll@r\'$ worth o7 7ertilizer";
+
+    @Before
+    public void setup() {
+        problem1 = new Problem1();
+    }
+
+    @Test
+    public void initializeMapTest() {
+        // Given
+        char key = 'f';
+        char expectedValue = '7';
+        // When
+        char actualValue = problem1.getMap().get('f');
+        // Then
+        Assert.assertEquals(expectedValue, actualValue);
+    }
+
+    @Test
+    public void replaceCharsWithIterationTest() {
+        // Given
+        String expectedOutput = output;
+        // When
+        String actualOutput = problem1.replaceCharsWithIteration(input);
+        // Then
+        Assert.assertEquals(expectedOutput, actualOutput);
+    }
+
+    @Test
+    public void replaceCharsWithRecursionTest() {
+        // Given
+        int startingIndex = 0;
+        String expectedOutput = output;
+        // When
+        String actualOutput = problem1.replaceCharsWithRecursion(input, startingIndex);
+        // Then
+        Assert.assertEquals(expectedOutput, actualOutput);
+    }
+
+
 }