/**
 * @author xusulong
 * input：已排序的序列A(从小到大)，数v
 * output：v在A中的位置（下标）
 */
public class BinarySearch {
	public static int binerySearch(int[] A, int key, int start, int end) {
		int index = 0;
		int middle = (start + end)/2;
		int middleKey = A[middle];
		if(key == middleKey) {
			index = middle;
		} else if(key < middleKey){
			index = binerySearch(A, key, start, middle);
		} else {
			index = binerySearch(A, key, middle + 1, end);
		}
		return index;
	}
	
	public static void main(String[] args) {
		int[] A = new int[] {1,2,3,4,5,6,7,8,9,10};
		int key = 1;
		System.out.println(binerySearch(A, key, 0, 9));
	}
}