Anagrams in string: naive sol. done

Author: rampatra

src/main/java/com/leetcode/strings/AnagramsInString.java

@@ -0,0 +1,52 @@
+package com.leetcode.strings;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Leetcode Problem: https://leetcode.com/problems/find-all-anagrams-in-a-string/
+ * 
+ * @author rampatra
+ * @since 2019-04-13
+ */
+public class AnagramsInString {
+
+    private static List<Integer> findAllAnagramsInTextNaive(String text, String pattern) {
+        List<Integer> indexes = new ArrayList<>();
+        
+        int textLen = text.length();
+        int patternLen = pattern.length();
+        
+        char[] patternChars = pattern.toCharArray();
+        Arrays.sort(patternChars); // takes O(m log m) time
+        String sortedPattern = String.valueOf(patternChars);
+        
+        String subText;
+        char[] subTextChars;
+        String sortedSubText;
+        
+        for (int i = 0; i <= textLen - patternLen; i++) { // loops n-m number of times
+            subText = text.substring(i, i + patternLen); 
+            subTextChars = subText.toCharArray();
+            Arrays.sort(subTextChars); // sorts m number of characters, takes O(m log m)
+            sortedSubText = String.valueOf(subTextChars);
+            
+            if (sortedSubText.equals(sortedPattern)) { // compare m characters takes m time
+                indexes.add(i);
+            }
+        }
+        return indexes;
+    }
+    
+    public static void main(String[] args) {
+        // basic use cases
+        System.out.println(findAllAnagramsInTextNaive("cbaebabacd", "abc"));
+        System.out.println(findAllAnagramsInTextNaive("abab", "ab"));
+        
+        // corner cases
+        System.out.println(findAllAnagramsInTextNaive("abab", ""));
+        System.out.println(findAllAnagramsInTextNaive("", "ab"));
+        System.out.println(findAllAnagramsInTextNaive("", ""));
+    }
+}