45 lines
1.2 KiB
Java
45 lines
1.2 KiB
Java
package Maths;
|
|
|
|
public class FindMaxRecursion {
|
|
public static void main(String[] args) {
|
|
int[] array = {2, 4, 9, 7, 19, 94, 5};
|
|
int low = 0;
|
|
int high = array.length - 1;
|
|
|
|
assert max(array, low, high) == 94;
|
|
assert max(array, array.length) == 94;
|
|
}
|
|
|
|
/**
|
|
* Get max of array using divide and conquer algorithm
|
|
*
|
|
* @param array contains elements
|
|
* @param low the index of the first element
|
|
* @param high the index of the last element
|
|
* @return max of {@code array}
|
|
*/
|
|
public static int max(int[] array, int low, int high) {
|
|
if (low == high) {
|
|
return array[low]; //or array[high]
|
|
}
|
|
|
|
int mid = (low + high) >>> 1;
|
|
|
|
int leftMax = max(array, low, mid); //get max in [low, mid]
|
|
int rightMax = max(array, mid + 1, high); //get max in [mid+1, high]
|
|
|
|
return Math.max(leftMax, rightMax);
|
|
}
|
|
|
|
/**
|
|
* Get max of array using recursion algorithm
|
|
*
|
|
* @param array contains elements
|
|
* @param len length of given array
|
|
* @return max value of {@code array}
|
|
*/
|
|
public static int max(int[] array, int len) {
|
|
return len == 1 ? array[0] : Math.max(max(array, len - 1), array[len - 1]);
|
|
}
|
|
}
|