karthikeya.bolla's soltions to chapter-1 of CTCI

java/Karthikeya_Bolla_Chapter_1/DuplicateCharacters1.java

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+/*
+ * Version: 1.0
+ * Author: Karthikeya Bolla
+ * 
+ * Cracking the coding interview - Question 1.1
+ * 
+ * finding if there are duplicate occurrences of characters in string
+ */
+
+import java.io.Console;
+import java.util.*;
+
+public class DuplicateCharacters1 
+{
+	//brute force approach i.e. looking through all characters one by one without using another data structure
+	public void Method1()
+	{
+		int count = 0;
+		System.out.println("Enter the string");
+		Scanner scan = new Scanner(System.in);
+		String inputString = scan.next();
+		char[] charArr = inputString.toCharArray();
+		for(int i=0;i<charArr.length;i++)
+		{
+			for(int j=i+1;j<charArr.length;j++)
+			{
+				if(charArr[i] != charArr[j])
+				{
+					continue;
+				}
+				else
+				{
+					count++;
+					System.out.println("repetitions exist");
+					break;
+				}
+			}
+		}
+		if(count == 0)
+		{
+			System.out.println("repetitions don't exist");
+		}
+	}
+
+	//using HashSet or TreeSet data structure i.e. using another data structure
+	public void Method2()
+	{
+		HashSet<Character> hset = new HashSet<Character>();
+		Scanner scan = new Scanner(System.in);
+		System.out.println("enter the string");
+		String inputString = scan.next();
+		char[] charArr = inputString.toCharArray();
+		int count = 0;
+		for(int i=0;i<charArr.length;i++)
+		{
+			if(hset.add(charArr[i]))
+			{
+				continue;
+			}
+			else
+			{
+				count++;
+				System.out.println("repetitions exist");
+				break;
+			}
+		}
+		if(count == 0)
+		{
+			System.out.println("repetitions don't exist");
+		}
+	}
+
+	public static void main(String[] args) 
+	{
+		DuplicateCharacters1 obj = new DuplicateCharacters1();
+		obj.Method1();
+		obj.Method2();
+	}
+}

java/Karthikeya_Bolla_Chapter_1/MatrixRotation.java

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+/*
+ * Version: 1.0
+ * Author: Karthikeya Bolla
+ * 
+ * Cracking the coding interview - Question 1.6
+ * 
+ * NxN Matrix rotation by 90 degrees and 270 degrees
+ */
+
+import java.io.*;
+import java.util.*;
+
+public class MatrixRotation 
+{
+	//rotation by 90 degrees
+	public void Rotation()
+	{
+		System.out.println("Enter the value of N");
+		Scanner scan = new Scanner(System.in);
+		int N = scan.nextInt();
+		int[][] originalMatrix = new int[N][N];
+		int[][] rotatedMatrix90 = new int[N][N];
+		int[][] rotatedMatrix270 = new int[N][N];
+
+		//generating some random matrix
+		for(int i=0;i<N;i++)
+		{
+			for(int j=0;j<N;j++)
+			{
+				originalMatrix[i][j] = 2*i+j;
+			}			
+		}
+		//90 degrees rotated matrix 
+		for(int i=0;i<N;i++)
+		{
+			for(int j=0;j<N;j++)
+			{
+				rotatedMatrix90[j][N - 1 - i] = originalMatrix[i][j];
+			}
+		}
+		//270 degrees rotated matrix (just out of interest) 
+		for(int i=0;i<N;i++)
+		{
+			for(int j=0;j<N;j++)
+			{
+				rotatedMatrix270[N - 1 - j][i] = originalMatrix[i][j];
+			}
+		}
+		//displaying values
+		System.out.println("original matrix:");
+		for(int i=0;i<N;i++)
+		{
+			for(int j=0;j<N;j++)
+			{
+				System.out.print(originalMatrix[i][j]+" ");
+			}
+			System.out.println();
+		}
+		System.out.println("90 degrees rotated matrix");
+		for(int i=0;i<N;i++)
+		{
+			for(int j=0;j<N;j++)
+			{
+				System.out.print(rotatedMatrix90[i][j]+" ");
+			}
+			System.out.println();
+		}
+		System.out.println("270 degrees rotated matrix");
+		for(int i=0;i<N;i++)
+		{
+			for(int j=0;j<N;j++)
+			{
+				System.out.print(rotatedMatrix270[i][j]+" ");
+			}
+			System.out.println();
+		}
+	}
+	public static void main(String[] args) 
+	{
+		MatrixRotation obj = new MatrixRotation();
+		obj.Rotation();
+	}
+}
+
+

java/Karthikeya_Bolla_Chapter_1/READ.me

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+
+The solutions to Chapter-1 are written by Karthikeya Bolla.
+
+Solutions are written in Java

java/Karthikeya_Bolla_Chapter_1/StringCompression.java

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+/*
+ * Version: 1.0
+ * Author: Karthikeya Bolla
+ * 
+ * Cracking the coding interview - Question 1.5
+ * 
+ * String compression
+ */
+import java.io.*;
+import java.util.*;
+
+public class StringCompression 
+{
+	public void Compress()
+	{
+		Scanner scan = new Scanner(System.in);
+		System.out.println("enter the string");
+		String originalStr = scan.nextLine();
+		//System.out.println(originalStr);
+		//System.out.println(originalStr.length());
+		int count = 0;
+		char prevChar = '\0';	
+		char[] charArr = originalStr.toCharArray();
+		StringBuffer newString = new StringBuffer();
+
+		for(int i=0;i<charArr.length;i++)
+		{
+			if(i == 0)
+			{
+				prevChar =  charArr[i];
+				count = 1;
+			}
+			else
+			{
+				if(charArr[i] == prevChar)
+				{
+					count++;
+				}
+				if(charArr[i] != prevChar)
+				{
+					newString.append(prevChar);
+					newString.append(count);
+					prevChar = charArr[i];
+					count = 1;
+				}
+				if(i == charArr.length-1)
+				{
+					newString.append(prevChar);
+					newString.append(count);
+				}
+			}
+		}
+		if(originalStr.length() < newString.length())
+		{
+			System.out.println(originalStr);
+		}
+		else
+		{
+			System.out.println(newString);
+		}
+	}
+	public static void main(String[] args) 
+	{
+		StringCompression obj = new StringCompression();
+		obj.Compress();
+	}
+}

java/Karthikeya_Bolla_Chapter_1/StringPermutation.java

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+/*
+ * Version: 1.0
+ * Author: Karthikeya Bolla
+ *  
+ * Cracking the coding interview - Question 1.3
+ * 
+ * check for string permutation
+ */
+
+import java.util.*;
+import java.io.*;
+
+public class StringPermutation 
+{
+
+	public void CheckPermutation()
+	{
+		Scanner scan = new Scanner(System.in);
+		System.out.println("Enter string1:");
+		String str1 = scan.next();
+		System.out.println("Enter string2");
+		String str2 = scan.next();
+
+		char[] str1CharArr = str1.toCharArray();
+		char[] str2CharArr = str2.toCharArray();
+
+		//sorting str1CharArr
+		int lengthStr1 = str1CharArr.length;
+		char temp;
+		for(int i=0;i<lengthStr1;i++)
+		{
+			for(int j=i+1;j<lengthStr1;j++)
+			{
+				if(str1CharArr[i] > str1CharArr[j])
+				{
+					temp = str1CharArr[i];
+					str1CharArr[i] = str1CharArr[j];
+					str1CharArr[j] = temp;
+				}
+			}
+		}
+
+		//sorting str2CharArr
+		int lengthStr2 = str2CharArr.length;
+		for(int i=0;i<lengthStr2;i++)
+		{
+			for(int j=i+1;j<lengthStr2;j++)
+			{
+				if(str2CharArr[i] > str2CharArr[j])
+				{
+					temp = str2CharArr[i];
+					str2CharArr[i] = str2CharArr[j];
+					str2CharArr[j] = temp;
+				}
+			}
+		}
+
+		//comparing
+		int count = 0;
+		for(int i=0;i<str1CharArr.length;i++)
+		{
+			if(str1CharArr[i] == str2CharArr[i])
+			{
+				continue;
+			}
+			else
+			{
+				count++;
+				System.out.println("The strings are not permutation of each other");
+				break;
+			}
+		}
+		if(count == 0)
+		{
+			System.out.println("Strings are permutation of each other");
+		}
+	}
+	public static void main(String[] args) 
+	{
+		StringPermutation obj = new StringPermutation();
+		obj.CheckPermutation();
+	}
+}

java/Karthikeya_Bolla_Chapter_1/Substring.java

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+/*
+ * Version: 1.0
+ * Author: Karthikeya Bolla
+ * 
+ * Cracking the coding interview - Question 1.8
+ * 
+ * checking if a string is part of actual string
+ */
+public class Substring 
+{
+	public void isSubstring(String str1, String str2)
+	{
+		String modifiedStr = "";
+		modifiedStr = modifiedStr + str1 + str1;
+		if(modifiedStr.contains(str2))
+		{
+			System.out.println("rotated string is contained in the original string");
+		}
+		else
+		{
+			System.out.println("rotated string is not contained in the original string");
+		}
+	}
+	public static void main(String[] args) 
+	{
+		Substring obj = new Substring();
+		String originalStr = "waterbottle";
+		String rotatedStr = "erbottlewat";
+		obj.isSubstring(originalStr, rotatedStr);
+	}
+}

java/Karthikeya_Bolla_Chapter_1/Whitespaces.java

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+/*
+ * Version: 1.0
+ * Author: Karthikeya Bolla
+ * Date: 12.29.2015
+ * 
+ * Cracking the coding interview - Question 1.4
+ * 
+ * Replace whitespaces with "%20"
+ */
+
+import java.util.*;
+import java.io.*;
+
+public class Whitespaces 
+{
+	public void editWhitespaces()
+	{
+		System.out.println("Enter string:");
+		Scanner scan = new Scanner(System.in);
+		String sentence = scan.nextLine();
+		String[] strArr = sentence.split(" ");
+		String finalString = "";
+
+		for(int i=0;i<strArr.length;i++)
+		{
+			if(i == 0)
+			{
+				finalString = strArr[i];
+			}
+			else
+			{
+				finalString = finalString +"%20"+strArr[i];
+			}
+		}
+		System.out.println(finalString);
+	}
+	public static void main(String[] args) 
+	{
+		Whitespaces obj = new Whitespaces();
+		obj.editWhitespaces();
+	}
+}