All programs

Author: AppyDev

AllPermutationsOfString.java

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+/* All permutations of a given String
+ * This algorithm taken O(n!) time since there are n! permutations possible */
+
+package codingProblems;
+import java.util.ArrayList;
+import java.util.Scanner;
+
+public class AllPermutationsOfString 
+{
+	public static void main(String args[])
+	{
+		Scanner in = new Scanner(System.in);
+		System.out.println("Enter a string to find permutations:");
+		System.out.println("All permutations:"+getPerm(in.next()));
+		in.close();
+	}
+	public static ArrayList<String> getPerm(String s)
+	{
+		ArrayList<String> perm = new ArrayList<String>();
+		if (s==null)
+			return null; //Error condition
+		else if(s.length() == 0) //base case
+		{
+			perm.add("");
+			return perm;
+		}
+
+		char c=s.charAt(0);
+		String remainder = s.substring(1);
+		ArrayList<String> words= getPerm(remainder);
+		for(String word:words)
+		{
+			for(int i=0;i<= word.length();i++)
+			{
+				perm.add(insertCharAt(word, c, i));
+			}
+		}
+		return perm;
+	}
+	public static String insertCharAt(String s, char c, int i)
+	{
+		String a=s.substring(0,i);
+		String b=s.substring(i);
+		return a+c+b;
+	}              
+}

Anagram.java

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+package codingProblems;
+import java.util.*;
+public class Anagram 
+{
+	public static boolean isAnagram(String firstWord, String secondWord) 
+	{
+	     char[] word1 = firstWord.replaceAll("[\\s]", "").toCharArray();
+	     char[] word2 = secondWord.replaceAll("[\\s]", "").toCharArray();
+	     Arrays.sort(word1);
+	     Arrays.sort(word2);
+	     return Arrays.equals(word1, word2);
+	}
+	public static void main(String args[]){
+		System.out.println(isAnagram("abca","cbaa"));
+	}
+}

AnagramComparator.java

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+package codingProblems;
+
+import java.util.Arrays;
+import java.util.Comparator;
+
+public class AnagramComparator implements Comparator<String>
+{
+	public int compare(String s1, String s2) 
+	{
+		return sortChars(s1).compareTo(sortChars(s2));
+	}
+	public String sortChars(String s) 
+	{
+		char[] content = s.toCharArray();
+		Arrays.sort(content);
+		return new String(content);
+	}
+	public static void main(String[] args)
+	{
+	    String[] strArray = new String[]{"abets","mates","baste","meats", "betas","beast", "steam", "tames", "beats", "teams"}; 
+	    sortArraysByAnagrams(strArray);
+	    for(String str : strArray){
+	        System.out.println(str);
+	    }
+
+	}
+	private static void sortArraysByAnagrams(String[] strArray) 
+	{
+	    Arrays.sort(strArray, new AnagramComparator());
+	}
+}

ArrayImplementationOfStack.java

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+/*
+ * Array Implementation of stack
+ */
+package codingProblems;
+
+public class ArrayImplementationOfStack 
+{
+	private int top;
+    int size;
+    int[] stack ;
+
+    public ArrayImplementationOfStack(int arraySize)
+    {
+        size=arraySize;
+        stack= new int[size];
+        top=-1;
+    }
+
+    public void push(int value)
+    {
+        if(top==size-1)
+        {
+            System.out.println("Stack is full, can't push a value");
+        }
+        else
+        {
+            top=top+1;
+            stack[top]=value;
+        }
+    }
+
+    public void pop()
+    {
+        if(!isEmpty())
+            top=top-1;
+        else
+        {
+            System.out.println("Can't pop...stack is empty");
+        }
+    }
+
+    public boolean isEmpty()
+    {
+        return top==-1;
+    }
+
+    public void display()
+    {
+        for(int i=0;i<=top;i++)
+        {
+            System.out.print(stack[i]+ " ");
+        }
+        System.out.println();
+    }
+}