68 lines
1.8 KiB
Java
68 lines
1.8 KiB
Java
|
/**
|
||
|
|
* Array utils for ints
|
||
|
|
* @author Isaac Shoebottom (3429069)
|
||
|
|
*/
|
||
|
|
|
||
|
|
public class IntArrayUtil {
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Appends an array to another array
|
||
|
|
* @param arrA First array in append
|
||
|
|
* @param arrB Second array in append
|
||
|
|
* @return Appended array
|
||
|
|
*/
|
||
|
|
public static int[] append (int[] arrA, int[] arrB) {
|
||
|
|
int appendedLength = arrA.length + arrB.length;
|
||
|
|
int[] appended = new int[appendedLength];
|
||
|
|
for(int i = 0; i < arrA.length; i++) {
|
||
|
|
appended[i] = arrA[i];
|
||
|
|
}
|
||
|
|
for(int i = 0; i < arrB.length; i++) {
|
||
|
|
appended[i + arrA.length] = arrB[i];
|
||
|
|
}
|
||
|
|
return appended;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Reverse the order of elements in a string
|
||
|
|
* @param arr The array to be reversed
|
||
|
|
* @return The reversed array
|
||
|
|
*/
|
||
|
|
public static int[] reverse (int[] arr) {
|
||
|
|
int[] reversed = new int[arr.length];
|
||
|
|
for(int i =0; i<arr.length; i++ ) {
|
||
|
|
reversed[i] = arr[i];
|
||
|
|
}
|
||
|
|
|
||
|
|
for(int i = 0; i < arr.length/2; i++) {
|
||
|
|
int temp = reversed[i];
|
||
|
|
reversed[i] = arr[(arr.length-1) - i];
|
||
|
|
reversed[(arr.length-1) - i] = temp;
|
||
|
|
}
|
||
|
|
|
||
|
|
return reversed;
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Subtracts every odd index from a string from every even index
|
||
|
|
* @param arr The array to perform math on
|
||
|
|
* @return The alternating sum of the array
|
||
|
|
*/
|
||
|
|
public static int alternatingSum (int[] arr) {
|
||
|
|
|
||
|
|
int positives = 0;
|
||
|
|
int negatives = 0;
|
||
|
|
boolean isPos = true;
|
||
|
|
for (int j : arr)
|
||
|
|
if (isPos) {
|
||
|
|
positives += j;
|
||
|
|
isPos = false;
|
||
|
|
} else {
|
||
|
|
negatives += j;
|
||
|
|
isPos = true;
|
||
|
|
}
|
||
|
|
|
||
|
|
return positives-negatives;
|
||
|
|
}
|
||
|
|
}
|