JavaAlgorithms/Searches/LinearSearch.java

package Searches;

import java.util.Random;
import java.util.stream.Stream;

/**
 * Linear search is the easiest search algorithm It works with sorted and unsorted arrays (an binary
 * search works only with sorted array) This algorithm just compares all elements of an array to
 * find a value
 *
 * <p>Worst-case performance O(n) Best-case performance O(1) Average performance O(n) Worst-case
 * space complexity
 *
 * @author Varun Upadhyay (https://github.com/varunu28)
 * @author Podshivalov Nikita (https://github.com/nikitap492)
 * @see BinarySearch
 * @see SearchAlgorithm
 */
public class LinearSearch implements SearchAlgorithm {

  /**
   * Generic Linear search method
   *
   * @param array List to be searched
   * @param value Key being searched for
   * @return Location of the key
   */
  @Override
  public <T extends Comparable<T>> int find(T[] array, T value) {
    for (int i = 0; i < array.length; i++) {
      if (array[i].compareTo(value) == 0) {
        return i;
      }
    }
    return -1;
  }

  public static void main(String[] args) {
    // just generate data
    Random r = new Random();
    int size = 200;
    int maxElement = 100;
    Integer[] integers =
        Stream.generate(() -> r.nextInt(maxElement)).limit(size).toArray(Integer[]::new);

    // the element that should be found
    Integer shouldBeFound = integers[r.nextInt(size - 1)];

    LinearSearch search = new LinearSearch();
    int atIndex = search.find(integers, shouldBeFound);

    System.out.println(
        String.format(
            "Should be found: %d. Found %d at index %d. An array length %d",
            shouldBeFound, integers[atIndex], atIndex, size));
  }
}