package Maths;

import java.util.Arrays;
import java.util.Random;

public class FindMinRecursion {

 /**
 * Driver Code
 */
 public static void main(String[] args) {
 Random rand = new Random();

 /* rand size */
 int size = rand.nextInt(100) + 1;
 int[] array = new int[size];

 /* init array with rand numbers */
 for (int i = 0; i < size; i++) {
 array[i] = rand.nextInt() % 100;
 }

 assert min(array, 0, array.length - 1) == Arrays.stream(array).min().getAsInt();
 assert min(array, array.length) == Arrays.stream(array).min().getAsInt();
 }

 /**
 * Get min 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 min of {@code array}
 */
 public static int min(int[] array, int low, int high) {
 if (low == high) {
 return array[low]; //or array[high]
 }

 int mid = (low + high) >>> 1;

 int leftMin = min(array, low, mid); //get min in [low, mid]
 int rightMin = min(array, mid + 1, high); //get min in [mid+1, high]

 return Math.min(leftMin, rightMin);
 }

 /**
 * Get min of array using recursion algorithm
 *
 * @param array contains elements
 * @param len length of given array
 * @return min value of {@code array}
 */
 public static int min(int[] array, int len) {
 return len == 1 ? array[0] : Math.min(min(array, len - 1), array[len - 1]);
 }
}