Interview Programs

public class P21_VowelsAndConsonantsInString {

	public static void main(String[] args) {
		
		String inputString = "Miss TecHack";
		
		char[] vowels = new char[5];
		char[] consonants = new char[inputString.length()];
		
		int v_flag = 0;
		int c_flag = 0;
		
		int v_count = 0;
		int c_count = 0;
		
		int index = 0;
		
		System.out.println("For input string '" + inputString + "' -");
		
		while(index < inputString.length()) {
			
			//check vowels
			if(inputString.charAt(index) == 'a' || inputString.charAt(index) == 'A'
					|| inputString.charAt(index) == 'e' || inputString.charAt(index) == 'E'
					|| inputString.charAt(index) == 'i' || inputString.charAt(index) == 'I'
					|| inputString.charAt(index) == 'o' || inputString.charAt(index) == 'O'
					|| inputString.charAt(index) == 'u' || inputString.charAt(index) == 'U'
			) {
				//set flag to zero to check for every index
				v_flag = 0;
				
				//check if vowel is already present in vowels array and set flag
				for(int i = 0; i < vowels.length; i++) {
					if(inputString.charAt(index) == vowels[i]) {
						v_flag++;
					}
				}
				//if not present in array, add it
				//increment count
				if(v_flag == 0) {
					vowels[v_count] = inputString.charAt(index);
					v_count++;
				}
			}
			//check consonants
			else if((inputString.charAt(index) >= 'a' && inputString.charAt(index) <= 'z')
					||
					(inputString.charAt(index) >= 'A' && inputString.charAt(index) <= 'Z')
					) {
				//set flag to zero to check for every index
				c_flag = 0;
				
				//check if consonant is already present in consonants array and set flag
				for(int i = 0; i < consonants.length; i++) {
					if(inputString.charAt(index) == consonants[i]) {
						c_flag++;
					}
				}
				//if not present in array, add it
				//increment count
				if(c_flag == 0) {
					consonants[c_count] = inputString.charAt(index);
					c_count++;
				}
			}
			index++;
		}
		System.out.println("Vowels count : " + v_count + "( " + 
				String.join(",", String.valueOf(vowels).trim().split("")) + " )");
		System.out.println("Consonants count : " + c_count + "( " + 
				String.join(",", String.valueOf(consonants).trim().split("")) + " )");
	}
}

public class P22_FindPermutationsOfAString {

	public static void main(String[] args) {
		findPermutation("","ABC");
	}

	private static void findPermutation(String perm, String word) {
		if (word.isEmpty()) {
			System.out.println(perm + word);
		} else {
			for (int i = 0; i < word.length(); i++) {
				//one character fix and then calculating permutations of others
				findPermutation(perm + word.charAt(i), word.substring(0, i) + word.substring(i + 1, word.length()));
			}
		}
	}
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;

public class P23_ReadUserInput {

	public static void main(String[] args) {
		ReadUserInput r = new ReadUserInput();
		r.scanner();
		r.bufferReader();
	}

	public void scanner() {
		Scanner s = new Scanner(System.in);
		System.out.println("Enter username");

		String userName = s.nextLine();
		System.out.println("Username is: " + userName);
	}

	public void bufferReader() {
		try {
			InputStreamReader isr = new InputStreamReader(System.in);
			BufferedReader br = new BufferedReader(isr);

			System.out.println("Enter Name");
			String name = br.readLine();
			System.out.println("Name: " + name);
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

public class P24_BinarySearch {

	public static void main(String[] args) {
		int[] list = {5,23,45,78,25,46,12,32,18,55};
		int search = 250;
		int index = binarySearch(list, search);
		if(index == -1) {
			System.out.println("Search key not found in list");
		} else {
			System.out.println("Search key found in list at index: " + index);
		}
	}

	public static int binarySearch(int[] input, int number) {
		int low = 0;
		int high = input.length - 1;
		while (high >= low) {
			int middle = (low + high) / 2;
			if (input[middle] == number) {
				return middle;
			} else if (input[middle] < number) {
				low = middle + 1;
			} else if (input[middle] > number) {
				high = middle - 1;
			}
		}
		return -1;
	}
}

import java.util.Arrays;

public class P25_BubbleSort {

	public static void main(String[] args) {
		int[] list = { 5, 23, 45, 78, 25, 46, 12, 32, 18, 55 };
		bubbleSort(list);
	}

	public static void bubbleSort(int[] numbers) {
		for (int i = 0; i < numbers.length; i++) {
			for (int j = numbers.length - 1; j > i; j--) {
				if (numbers[j] < numbers[j - 1]) {
					swap(numbers, j, j - 1);
				}
			}
		}
		System.out.println("Sorted Array using Bubble sort algorithm " + Arrays.toString(numbers));
	}

	public static void swap(int[] array, int from, int to) {
		int temp = array[from];
		array[from] = array[to];
		array[to] = temp;
	}
}

import java.util.Arrays;

public class P26_QuickSort {

	int[] list = { 5, 23, 45, 78, 25, 46, 12, 32, 18, 55 };
	int length = list.length;

	public static void main(String[] args) {
		QuickSort qs = new QuickSort();
		
		if (qs.list == null || qs.list.length == 0) {
			return;
		}
		qs.quickSort(0, qs.length - 1);
		System.out.println("Sorted array :" + Arrays.toString(qs.list));

	}

	private void quickSort(int low, int high) {
		int i = low;
		int j = high;
		int mid = list[low + (high - low) / 2];
		
		while (i <= j) {
			while (list[i] < mid) {
				i++;
			}
			while (list[j] > mid) {
				j--;
			}
			if (i <= j) {
				swap(i, j);
				i++;
				j--;
			}
			if (low < j) {
				quickSort(low, j);
			}
			if (i < high) {
				quickSort(i, high);
			}
		}
	}

	private void swap(int i, int j) {
		int temp = list[i];
		list[i] = list[j];
		list[j] = temp;
	}
}

import java.util.Arrays;

public class P27_InsertionSort {

	public static void main(String[] args) {
		int[] list = { 5, 23, 45, 78, 25, 46, 12, 32, 18, 55 };
		insertionSort(list);
		System.out.println("Sorted Array using Insertion sort algorithm : " + Arrays.toString(list));
	}

	public static void insertionSort(int[] unsortedList) {
		for (int i = 1; i < unsortedList.length; i++) {
			int current = unsortedList[i];
			int j = i;
			while (j > 0 && unsortedList[j - 1] > current) {
				unsortedList[j] = unsortedList[j - 1];
				j--;
			}
			unsortedList[j] = current;
		}
	}
}