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ArrayUtil.java
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ArrayUtil.java
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package com.aman.data_structures;
public class ArrayUtil {
public static void main(String[] args) {
// ArrayUtil arrayUtil = new ArrayUtil();
// arrayUtil.arrayDemo();
// creating an array
int[] arr = {1, 2, 3, 4, 5, 6, 7};
printArray(arr);
// System.out.println(arr.length);
// calling removeEven function & printing the result
// int[] result = removeEven(arr);
// printArray(result);
// calling reverse method & printing the result
// reverse(arr, 0, arr.length-1);
// printArray(arr);
// calling minimum method & printing the result
// System.out.println("The minimum value in the array is : " + minimum(arr));
// calling findSecondMax & displaying the result
// System.out.println("The second maximum value in the array is : " + findSecondMax(arr));
// calling moveZeros method & printing the result
// moveZeros(arr, arr.length);
// printArray(arr);
// calling resize method & printing the result
// arr = resize(arr, 10);
// System.out.println(arr.length);
// calling findMissingNumber method & displaying it
// System.out.println("The missing number int the array is : " + findMissingNumber(arr));
// calling isPalindrome method & displaying the result
// System.out.println(isPalindrome("bob"));
// calling sortedSquares method & printing the result
// int[] arr = {-4, -1, 0, 3, 10};
// printArray(arr);
// int[] arr2 = sortedSquares(arr);
// printArray(arr2);
// calling arrangeMaxMin method & printing the result
arrangeMaxMin(arr);
printArray(arr);
}
// print an array
public static void printArray(int[] arr){
int n = arr.length;
for(int i = 0; i < n; i++){
System.out.print(arr[i] + " ");
}
System.out.println();
}
// creating an array
public void arrayDemo(){
int[] myArray = new int[5];
myArray[0] = 5;
myArray[1] = 4;
myArray[2] = 3;
myArray[3] = 2;
myArray[4] = 1;
printArray(myArray);
// printing length of array
System.out.println("Length of the array: " + myArray.length);
// printing last element of the array
System.out.println("Last element of the array : " + myArray[myArray.length - 1]);
// creating & printing an array
int[] arr = {5, 4, 3, 2, 1};
printArray(arr);
}
// remove even integer from an array
public static int[] removeEven(int[] arr){
int oddCount = 0;
for(int i = 0; i < arr.length; i++){
if(arr[i] % 2 != 0){
oddCount++;
}
}
int[] result = new int[oddCount];
int index = 0;
for(int i = 0; i < arr.length; i++){
if(arr[i] % 2 != 0){
result[index] = arr[i];
index++;
}
}
return result;
}
// reverse the array
public static void reverse(int[] numbers, int start, int end){
while(start < end){
int temp = numbers[start];
numbers[start] = numbers[end];
numbers[end] = temp;
start++;
end--;
}
}
// find the minimum value
public static int minimum(int[] arr){
if(arr == null || arr.length == 0){
throw new IllegalArgumentException("Invalid Input");
}
int min = arr[0];
for(int i = 1; i < arr.length; i++){
if(arr[i] < min){
min = arr[i];
}
}
return min;
}
// find the second max value
public static int findSecondMax(int[] arr){
int max = Integer.MIN_VALUE;
int secondMax = Integer.MIN_VALUE;
for(int i = 0; i < arr.length; i++){
if(arr[i] > max){
secondMax = max;
max = arr[i];
}
else if(arr[i] > secondMax && arr[i] != max){
secondMax = arr[i];
}
}
return secondMax;
}
// move zeroes to the end
public static void moveZeros(int[] arr, int n){
int j = 0; // will focus on zeroth elements
for(int i = 0; i < n; i++){ // will focus on non-zero elements
if(arr[i] != 0 && arr[j] == 0){
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
if(arr[j] != 0){
j++;
}
}
}
// resize an array
public static int[] resize(int[] arr, int capacity){
int[] temp = new int[capacity];
for(int i = 0; i < arr.length; i++) {
temp[i] = arr[i];
}
return temp;
}
// find missing number in an array
public static int findMissingNumber(int[] arr){
int n = arr.length + 1;
int sum = n * (n + 1) / 2;
for(int num : arr){
sum = sum - num;
}
return sum;
}
// check if palindrome
public static boolean isPalindrome(String word){
char[] charArrayWord = word.toCharArray();
int start = 0;
int end = word.length() - 1;
while(start < end){
if(charArrayWord[start] != charArrayWord[end]){
return false;
}
start++;
end--;
}
return true;
}
// squares of sorted array
public static int[] sortedSquares(int[] arr){
int n = arr.length;
int[] result = new int[n];
int i = 0;
int j = n - 1;
for(int k = n - 1; k >= 0; k--){
if(Math.abs(arr[i]) > Math.abs(arr[j])){
result[k] = arr[i] * arr[i];
i++;
}
else{
result[k] = arr[j] * arr[j];
j--;
}
}
return result;
}
// rearrange sorted array in max/min form
public static void arrangeMaxMin(int[] arr){
int maxIdx = arr.length - 1;
int minIdx = 0;
int max = arr[maxIdx] + 1;
for(int i = 0; i < arr.length; i++){
if(i % 2 == 0){
arr[i] = arr[i] + (arr[maxIdx] % max) * max;
maxIdx--;
}
else{
arr[i] = arr[i] + (arr[minIdx] % max) * max;
minIdx++;
}
}
for(int i = 0; i < arr.length; i++){
arr[i] = arr[i]/max;
}
}
}