finish first assignment and pass all tests - Tsung-Yu Lin

StringArrayUtils.java

@@ -1,5 +1,7 @@
-
-
+import java.util.*;
+import java.util.HashMap;
+import java.util.Map;
+import java.lang.String;
 /**
  * Created by Yang on 1/23/20.
  */
@@ -9,31 +11,30 @@ public class StringArrayUtils {
      * @return first element of specified array
      */ // TODO
     public static String getFirstElement(String[] array) {
-        return null;
+        return array[0];
     }
-
     /**
      * @param array array of String objects
      * @return second element in specified array
      */
     public static String getSecondElement(String[] array) {
-        return null;
+        return array[1];
     }
 
     /**
      * @param array array of String objects
      * @return last element in specified array
      */ // TODO
     public static String getLastElement(String[] array) {
-        return null;
+        return array[array.length-1];
     }
 
     /**
      * @param array array of String objects
      * @return second to last element in specified array
      */ // TODO
     public static String getSecondToLastElement(String[] array) {
-        return null;
+        return array[array.length-2];
     }
 
     /**
@@ -42,22 +43,34 @@ public static String getSecondToLastElement(String[] array) {
      * @return true if the array contains the specified `value`
      */ // TODO
     public static boolean contains(String[] array, String value) {
-        return false;
+        return Arrays.asList(array).contains(value);
     }
 
     /**
      * @param array of String objects
      * @return an array with identical contents in reverse order
      */ // TODO
     public static String[] reverse(String[] array) {
-        return null;
+        String[] reverseArray = new String[array.length];
+        int index=0;
+        for(int i=array.length-1;i>=0;--i){
+            reverseArray[index++]=array[i];
+        }
+        return reverseArray;
     }
 
     /**
      * @param array array of String objects
      * @return true if the order of the array is the same backwards and forwards
      */ // TODO
     public static boolean isPalindromic(String[] array) {
+        String[] reverseArray = new String[array.length];
+        int index=0;
+        for(int i=array.length-1;i>=0;--i){
+            reverseArray[index++]=array[i];
+        }
+        if(Arrays.equals(array,reverseArray))
+            return true;
         return false;
     }
 
@@ -66,7 +79,25 @@ public static boolean isPalindromic(String[] array) {
      * @return true if each letter in the alphabet has been used in the array
      */ // TODO
     public static boolean isPangramic(String[] array) {
-        return false;
+        boolean[] alphabetCheck= new boolean[26];
+        for(String s:array){
+            int index=0;
+            char[] chars = s.toCharArray();
+            for(char c:chars){
+                if ('A' <= c && c <= 'Z')
+                    index = c - 'A';
+                else if ('a' <= c && c <= 'z')
+                    index = c - 'a';
+                else
+                    continue;
+                alphabetCheck[index]=true;
+            }
+
+        }
+        for (int i = 0; i <= 25; i++)
+            if (alphabetCheck[i] == false)
+                return false;
+        return true;
     }
 
     /**
@@ -75,7 +106,14 @@ public static boolean isPangramic(String[] array) {
      * @return number of occurrences the specified `value` has occurred
      */ // TODO
     public static int getNumberOfOccurrences(String[] array, String value) {
-        return 0;
+        Map<String, Integer> map = new HashMap<String, Integer>();
+        for(String s:array){
+            if(map.containsKey(s))
+                map.put(s,map.get(s)+1);
+            else
+                map.put(s,1);
+        }
+        return map.get(value);
     }
 
     /**
@@ -84,23 +122,48 @@ public static int getNumberOfOccurrences(String[] array, String value) {
      * @return array with identical contents excluding values of `value`
      */ // TODO
     public static String[] removeValue(String[] array, String valueToRemove) {
-        return null;
+        List<String> removedList = new ArrayList<String>(Arrays.asList(array));
+        removedList.remove(valueToRemove);
+        return removedList.toArray(new String[0]);
     }
 
     /**
      * @param array array of chars
      * @return array of Strings with consecutive duplicates removes
      */ // TODO
     public static String[] removeConsecutiveDuplicates(String[] array) {
-        return null;
+        int index=1;
+        for(int i=1;i<array.length;i++){
+            if(array[i]!=array[index-1])
+                array[index++] = array[i];
+        }
+        String[] ans=new String[index];
+        for(int i=0;i<index;i++)
+            ans[i]=array[i];
+        return ans;
     }
 
     /**
      * @param array array of chars
      * @return array of Strings with each consecutive duplicate occurrence concatenated as a single string in an array of Strings
      */ // TODO
     public static String[] packConsecutiveDuplicates(String[] array) {
-        return null;
+
+        String tmp=array[0];
+        List<String> list=new ArrayList<String>();
+        for(int i=1;i<array.length;i++){
+
+            if(array[i]!=array[i-1]){
+                list.add(tmp);
+                tmp=array[i];
+            }
+            else
+                tmp+=array[i];
+
+        }
+        list.add(tmp);
+        String[] ans = list.toArray(new String[list.size()]);
+        return ans;
     }