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Copy pathLeftRotation.java
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97 lines (80 loc) · 2.63 KB
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package mycode;
import java.util.*;
/**
* Created by nikoo28 on 9/2/20 12:05 AM
*/
public class LeftRotation {
// Helper function to reverse an array from start index to end index
public void reverse(int[] nums, int start, int end) {
while (start < end) {
int temp = nums[start];
nums[start] = nums[end];
nums[end] = temp;
start++;
end--;
}
}
public void rotateLeftUsingReverse(int[] arr, int k) {
// Reverse all numbers
reverse(arr, 0, arr.length - 1);
// Reverse first arr.length-k numbers
reverse(arr, 0, arr.length - k - 1);
// Reverse last k numbers
reverse(arr, arr.length - k, arr.length - 1);
}
public void rotateLeftUsingBruteForce(int[] arr, int k) {
// Rotate the array k times
for (int i = 0; i < k; i++) {
int j, temp;
temp = arr[0];
// Perform rotation for each iteration
for (j = 0; j < arr.length - 1; j++)
arr[j] = arr[j + 1];
arr[j] = temp;
}
}
public void rotateLeft(int[] arr, int k) {
int[] temp = new int[k];
// Store the first k elements in a temp array
for (int i = 0; i < temp.length; i++) {
temp[i] = arr[i];
}
// Shift rest of the arr[]
for (int i = 0; i < arr.length - k; i++) {
arr[i] = arr[i + k];
}
// Store back the k elements
int idx = 0;
for (int i = arr.length - k; i < arr.length; i++) {
arr[i] = temp[idx++];
}
}
public void rotateLeftUsingQueue(int k, int[] arr) {
Queue<Integer> queue = new LinkedList<>();
for (int j : arr) {
queue.add(j);
}
for (int i = 0; i < k; i++) {
queue.add(queue.poll());
}
int i = 0;
while (!queue.isEmpty()) {
arr[i++] = queue.poll();
}
}
public static void main(String[] args) {
int[] arr = new int[]{1, 2, 3, 4, 5};
LeftRotation leftRotation = new LeftRotation();
leftRotation.rotateLeftUsingReverse(arr, 2);
System.out.println(Arrays.toString(arr));
arr = new int[]{1, 2, 3, 4, 5};
leftRotation.rotateLeftUsingBruteForce(arr, 2);
System.out.println(Arrays.toString(arr));
arr = new int[]{1, 2, 3, 4, 5};
leftRotation.rotateLeft(arr, 2);
System.out.println(Arrays.toString(arr));
arr = new int[]{1, 2, 3, 4, 5};
leftRotation.rotateLeftUsingQueue(2, arr);
System.out.println(Arrays.toString(arr));
}
}