public class BinarySearch {
	
	private int[] array;
	private int index;
	private int min;
	private int max;
	
	public BinarySearch(int[] array) {
		this.array = array;
		min = 0;
		max = this.array.length - 1;
	}
	/**
	 * 返回array中key下標，返回-1代表沒找到，使用遞迴方式
	 * @param key
	 * @return
	 */
	public int search(int key){
		index = (min + max) / 2;
		if(array[index] == key)
			return index;
		else if(min > max)
			return -1;
		else{
			if(array[index] > key)
				max = index - 1;
			else
				min = index + 1;
		}
		return search(key);
	}
	/**
	 * 返回array中key下標，返回-1代表沒找到，使用非遞迴方式
	 * @param key
	 * @return
	 */
	public int search2(int key){
		while(true){
			index = (min + max) / 2;
			if(array[index] == key)
				return index;
			else if(min > max)
				return -1;
			else{
				if(array[index] > key)
					max = index - 1;
				else
					min = index + 1;
			}
		}
	}
}