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ReverseArrayInPlace.java
42 lines (37 loc) · 1.24 KB
/
ReverseArrayInPlace.java
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/**
* Created by Devang on 19-Feb-17.
*/
public class ReverseArrayInPlace {
public static void main(String[] args) {
/* Read input and create array */
int n = 5;
int k = 3;
int [] array = {1, 2, 3, 4, 5};
/* Rotate array (in place) using 3 reverse operations */
k = k % n; // to account for cases where k > n
reverse(array, 0, array.length - 1);
reverse(array, 0, k - 1);
reverse(array, k, array.length - 1);
/* Print output */
for (int i = 0; i < array.length ; i++) {
System.out.println(array[i] +" ");
}
}
/* Reverses array from "start" to "end" inclusive */
private static void reverse(int [] array, int start, int end) {
if (array == null || start < 0 || start >= array.length ||
end < 0 || end >= array.length || start >= end) {
return;
}
int mid = (start + end) / 2;
for (int i = start; i <= mid; i++) {
int offset = i - start;
swap(array, start + offset, end - offset);
}
}
private static void swap (int [] array, int i, int j) {
int temp = array[i];
array[i] = array[j];
array[j] = temp;
}
}