tk.hongkailiu.test.app.search.BinarySearch Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of test-app Show documentation

The newest version!

package tk.hongkailiu.test.app.search;

import java.util.List;

public class BinarySearch {

    public static boolean binarySearch(final List numbers, final Integer value) {
        if (numbers.isEmpty()) {
            return false;
        }

        final Integer comparison = numbers.get(numbers.size() / 2);
        if (value.equals(comparison)) {
            return true;
        }

        if (value < comparison) {
            return binarySearch(numbers.subList(0, numbers.size() / 2), value);
        } else {
            return binarySearch(numbers.subList(numbers.size() / 2 + 1, numbers.size()), value);
        }
    }

    /**
     * hongkai: implement by iteration
     *
     * @param numbers td
     * @param value td
     * @return td
     */
    public static boolean binarySearchIteration(final List numbers, final Integer value) {
        if (numbers == null || numbers.isEmpty()) {
            return false;
        }

        int begin = 0;
        int end = numbers.size() - 1;

        do {
            int middle = begin + (end - begin) / 2;
            final Integer comparison = numbers.get(middle);
            if (value.equals(comparison)) {
                return true;
            }
            if (value < comparison) {
                end = middle - 1;
            } else {
                begin = middle + 1;
            }
        } while (begin <= end);

        return false;
    }


}