problem 1

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

@@ -1,4 +1,34 @@
 package io.zipcoder;
 
+import java.util.HashMap;
+
 public class Problem1 {
+
+    public String changeLetters(String str,HashMap<Character,Character> changeMap){
+        StringBuilder builder = new StringBuilder();
+        for(int i = 0;i<str.length();i++){
+            Character currentChar = str.charAt(i);
+            if(changeMap.containsKey(Character.toLowerCase(currentChar))){
+                currentChar = changeMap.get(Character.toLowerCase(currentChar));
+            }
+            builder.append(currentChar);
+        }
+        return builder.toString();
+    }
+
+    public String recursion(String str,HashMap<Character,Character> changeMap){
+        if(str.length() == 0){
+            return "";
+        }
+        Character currentChar = str.charAt(0);
+        if(changeMap.containsKey(Character.toLowerCase(currentChar))){
+            currentChar = changeMap.get(Character.toLowerCase(currentChar));
+        }
+        return currentChar + recursion(str.substring(1),changeMap);
+
+    }
+
+
+
+    // use replace
 }

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

@@ -1,4 +1,39 @@
 package io.zipcoder;
 
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.HashMap;
+
 public class Problem1Test {
+    Problem1 problem1;
+    HashMap<Character,Character> changeMap;
+    String input;
+
+    @Before
+    public void setUp() {
+        changeMap = new HashMap<Character, Character>();
+        changeMap.put('f', '7');
+        changeMap.put('s', '$');
+        changeMap.put('1', '!');
+        changeMap.put('a', '@');
+        problem1 = new Problem1();
+        input = "The Farmer went to the store to get 1 dollar’s worth of fertilizer";
+
+    }
+
+    @Test
+    public void withLoop(){
+        String expected = "The 7@rmer went to the $tore to get ! doll@r’$ worth o7 7ertilizer";
+        String actual = problem1.changeLetters(input,changeMap);
+        Assert.assertEquals(expected,actual);
+    }
+
+    @Test
+    public void withRecursion(){
+        String expected = "The 7@rmer went to the $tore to get ! doll@r’$ worth o7 7ertilizer";
+        String actual = problem1.recursion(input,changeMap);
+        Assert.assertEquals(expected,actual);
+    }
 }