이진탐색 알고리즘 (Binary Search)

Main.java

/**
 * 이진탐색 알고리즘 (Binary Search)
 * 
 * @author devetue
 */
public class Main {
	public static void main(String args[]) {
		int[] numbers = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
		int key = 7;
		int start = 0;
		int end = numbers.length - 1;
		int res = -1;

		while (start <= end) {
			int middle = (start + end) / 2;

			if (numbers[middle] < key) {
				start = middle + 1;
			}

			else if (numbers[middle] > key) {
				end = middle - 1;
			}

			else {
				res = middle;
				break;
			}
		}

		if (res == -1) {
			System.out.println("There isn't key here.");
		}

		else {
			System.out.println("key's index is " + res + ".");
		}
	}
}