Add Algorithm

Author: jbee37142

src/test/java/algorithm/CharacterCompressWithLength.java

@@ -0,0 +1,18 @@
+package algorithm;
+
+import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+public class CharacterCompressWithLength {
+
+    @Test
+    public void test() {
+        assertThat("", is(testFunction()));
+    }
+
+    public String testFunction() {
+        return "";
+    }
+}

src/test/java/algorithm/IsAnagram.java

@@ -0,0 +1,55 @@
+package algorithm;
+
+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 IsAnagram {
+
+    /*
+        TASK
+        주어진 문자열이 애너그램인지를 판단한다.
+     */
+
+    // 방법 1. O(nlogn) : 정렬 후에 비교하기
+    // 방법 2. O(n) : 문자열 개수를 세서 비교하기
+
+    @Test
+    public void 애너그램판별하기() {
+        assertThat(true, is(애너그램판별_USE_MAP("arc", "car")));
+        assertThat(true, is(애너그램판별_USE_MAP("caaabbb", "abababc")));
+        assertThat(false, is(애너그램판별_USE_MAP("caabbbb", "abababc")));
+        assertThat(false, is(애너그램판별_USE_MAP("arc", "carr")));
+        assertThat(false, is(애너그램판별_USE_MAP("arc", "caz")));
+    }
+
+    private boolean 애너그램판별_USE_MAP(String str1, String str2) {
+        if (str1.length() != str2.length()) return false;
+
+        Map<Character, Integer> strMap = new HashMap<Character, Integer>();
+
+        for (char c : str1.toCharArray()) {
+            if (strMap.containsKey(c)) {
+                strMap.put(c, strMap.get(c) + 1);
+            } else {
+                strMap.put(c, 1);
+            }
+        }
+
+        for (char c : str2.toCharArray()) {
+            if (!strMap.containsKey(c)) {
+                return false;
+            }
+            if (strMap.get(c) == 0) {
+                return false;
+            }
+            strMap.put(c, strMap.get(c) - 1);
+        }
+
+        return true;
+    }
+}

src/test/java/algorithm/StringParseToInt.java

@@ -0,0 +1,30 @@
+package algorithm;
+
+import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+public class StringParseToInt {
+
+    /*
+        TASK
+        주어진 문자열을 int 형으로 변환한다.
+    */
+
+    @Test
+    public void toIntFromString() {
+        assertThat(123, is(toIntFromString("123")));
+    }
+
+    private int toIntFromString(String str) {
+//        return Integer.parseInt(str);
+        char[] strArr = str.toCharArray();
+        int base = 0;
+        for (char c : strArr) {
+            base *= 10;
+            base += c - '0';
+        }
+        return base;
+    }
+}

src/test/java/algorithm/UniqueCharacterInString.java

@@ -0,0 +1,51 @@
+package algorithm;
+
+import org.junit.Test;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+public class UniqueCharacterInString {
+
+    /*
+        TASK
+        주어진 문자열에서 문자열을 구성하고 있는 각각의 문자열들이 고유한지를 판단한다.
+     */
+
+    @Test
+    public void 문자열내에서_각문자열이_고유한가() {
+        assertThat(true, is(이중포문을_사용한_방법("abcd")));
+        assertThat(true, is(이중포문을_사용한_방법("abcdefghij")));
+        assertThat(false, is(이중포문을_사용한_방법("abccde")));
+        assertThat(false, is(이중포문을_사용한_방법("abca")));
+
+        assertThat(true, is(HashSet을_사용한_방법("abcd")));
+        assertThat(true, is(HashSet을_사용한_방법("abcdefghij")));
+        assertThat(false, is(HashSet을_사용한_방법("abccde")));
+        assertThat(false, is(HashSet을_사용한_방법("abca")));
+    }
+
+    private boolean 이중포문을_사용한_방법(String str) {
+        char[] strArr = str.toCharArray();
+        for (int i = 0; i < strArr.length - 1; i++) {
+            for (int j = i + 1; j < strArr.length; j++) {
+                if (strArr[i] == strArr[j]) return false;
+            }
+        }
+        return true;
+    }
+
+    private boolean HashSet을_사용한_방법(String str) {
+        Set<Character> strSet = new HashSet<Character>();
+        for (char c : str.toCharArray()) {
+            if (strSet.contains(c)) {
+                return false;
+            }
+            strSet.add(c);
+        }
+        return true;
+    }
+}