Add Algorithm

Author: jbee37142

build.gradle

@@ -3,7 +3,7 @@ version '1.0-SNAPSHOT'
 
 apply plugin: 'java'
 
-sourceCompatibility = 1.5
+sourceCompatibility = 1.8
 
 repositories {
     mavenCentral()

src/test/java/algorithm/CharacterCompressWithLength.java

@@ -2,17 +2,63 @@
 
 import org.junit.Test;
 
+import java.util.HashMap;
+import java.util.Map;
+
 import static org.hamcrest.CoreMatchers.is;
 import static org.junit.Assert.assertThat;
 
 public class CharacterCompressWithLength {
 
+    /*
+        TASK
+        주어진 문자열을 길이와 함께 적어주면서 압축을 한다.
+     */
+
     @Test
     public void test() {
-        assertThat("", is(testFunction()));
+        assertThat(null, is(RunLengthCompress_USE_HASHMAP(null)));
+        assertThat("a3b3c3", is(RunLengthCompress_USE_HASHMAP("aaabbbccc")));
+        assertThat("a3b3c4", is(RunLengthCompress_USE_HASHMAP("aabbacbccc")));
+
+        assertThat("a3b3c3", is(RunLengthCompress("aaabbbccc")));
     }
 
-    public String testFunction() {
-        return "";
+    private String RunLengthCompress_USE_HASHMAP(String str) {
+        if (str == null) return null;
+
+        Map<Character, Integer> charCounter = new HashMap<>(str.length());
+
+        for (char c : str.toCharArray()) {
+            if (charCounter.containsKey(c)) {
+                charCounter.put(c, charCounter.get(c) + 1);
+            } else {
+                charCounter.put(c, 1);
+            }
+        }
+        StringBuilder sb = new StringBuilder();
+        charCounter.forEach((chr, count) -> sb.append(chr + count.toString()));
+        return sb.toString();
+    }
+
+    private String RunLengthCompress(String str) {
+        if (str == null) return null;
+
+        char[] ca = str.toCharArray();
+        String result = "";
+        int count = 1;
+        char prev = ca[0];
+
+        for (int i = 1; i < ca.length; i++) {
+            if (prev == ca[i]) {
+                count++;
+            } else {
+                result = result + prev + count;
+                count = 1;
+                prev = ca[i];
+            }
+        }
+        result = result + prev + count;
+        return result;
     }
 }

src/test/java/algorithm/IsAnagram.java

@@ -30,7 +30,7 @@ public void test() {
     private boolean 애너그램판별_USE_MAP(String str1, String str2) {
         if (str1.length() != str2.length()) return false;
 
-        Map<Character, Integer> strMap = new HashMap<Character, Integer>();
+        Map<Character, Integer> strMap = new HashMap<>();
 
         for (char c : str1.toCharArray()) {
             if (strMap.containsKey(c)) {

src/test/java/algorithm/UniqueCharacterInString.java

@@ -39,7 +39,7 @@ public void test() {
     }
 
     private boolean HashSet을_사용한_방법(String str) {
-        Set<Character> strSet = new HashSet<Character>();
+        Set<Character> strSet = new HashSet<>();
         for (char c : str.toCharArray()) {
             if (strSet.contains(c)) {
                 return false;