pradeepkumar24rk
diff --git a/‎ArrayBasedProblems/SubSequenceInArray.java
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+2Lines changed: 2 additions & 0 deletions b/‎ArrayBasedProblems/SubSequenceInArray.java
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+2Lines changed: 2 additions & 0 deletions
diff --git a/‎Recursion/LetterCombination.java
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+20Lines changed: 20 additions & 0 deletions b/‎Recursion/LetterCombination.java
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+20Lines changed: 20 additions & 0 deletions
diff --git a/‎Recursion/Permutations.java
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+59Lines changed: 59 additions & 0 deletions b/‎Recursion/Permutations.java
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+59Lines changed: 59 additions & 0 deletions
@@ -1,6 +1,7 @@
 package ArrayBasedProblems;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 
 public class SubSequenceInArray {
 
@@ -39,6 +40,7 @@ private static void listSubSequence() { // time complexity - o(n*2^n) duplicatio
 
     private static void listSubSequenceDuplicate() { // time complexity - o(n*2^n) with duplication allow
         int nums[] = { 1, 2, 2 };
+        Arrays.sort(nums);
         ArrayList<ArrayList<Integer>> outer = new ArrayList<>();
         outer.add(new ArrayList<>());
         int start = 0, end = 0;
 
@@ -0,0 +1,20 @@
+package Recursion;
+
+public class LetterCombination {
+
+    private static void pad(String str,String ans) {
+        if(str.length()==0) {
+            System.out.println(ans);
+            return;
+        }
+        
+        int digit = str.charAt(0) - '0';
+        for(int i = (digit-1)*3;i<(digit*3);i++) {
+            char ch = (char) ('a'+i);
+            pad(str.substring(1), ans+ch);
+        }
+    }
+    public static void main(String[] args) {
+        pad("12", "");
+    }
+}
@@ -0,0 +1,59 @@
+package Recursion;
+
+import java.util.ArrayList;
+
+public class Permutations {
+
+    private static void permutation(String str,String ans) {
+        if(str.length() == 0) {
+            System.out.println(ans);
+            return;
+        }
+        char ch = str.charAt(0);
+        for(int i = 0;i<=ans.length();i++) {
+            String f = ans.substring(0, i);
+            String e = ans.substring(i,ans.length());
+            permutation(str.substring(1), f+ch+e);
+        }
+    }
+    
+    private static ArrayList<String> permutationArrayList(String str,String ans) {
+        if(str.length() == 0) {
+            ArrayList<String> list = new ArrayList<>();
+            list.add(ans);
+            return list;
+        }
+        char ch = str.charAt(0);
+        ArrayList<String> arr = new ArrayList<>();
+        for(int i = 0;i<=ans.length();i++) {
+            String f = ans.substring(0, i);
+            String e = ans.substring(i,ans.length());
+           
+           arr.addAll(permutationArrayList(str.substring(1), f+ch+e));
+        }
+        return arr;
+    }
+    
+    private static int permutationCount(String str,String ans) {
+        if(str.length() == 0) {
+            // System.out.println(ans);
+            return 1;
+        }
+        int count = 0;
+        char ch = str.charAt(0);
+        for(int i = 0;i<=ans.length();i++) {
+            String f = ans.substring(0, i);
+            String e = ans.substring(i,ans.length());
+            count+=permutationCount(str.substring(1), f+ch+e);
+        }
+        return count;
+    }
+    
+    public static void main(String[] args) {
+        String str = "abc";
+        permutation(str,"");
+        System.out.println(permutationArrayList(str,""));
+        System.out.println(permutationCount("abcd",""));
+        
+    }
+}