折半查找变形

折半查找思想的应用：

public class BinarySearch {
	
	//将有序数组分两半，将前一部分有序的数组，放到后面
	//如[1,2,3,4,5,6,7,8,9,10] 换成[5,6,7,8,9,10,1,2,3,4]
	//然后对这样的数组进行查找

	//测试代码
	public static void main(String[] args) {		
		int [] array = {5,6,7,8,9,10, 1,2,3,4};			
		//查找3， 并打印其对应下标
		System.out.println(arrange(array, 3));
		}
		
//	查找算法
	public static int arrange (int [] array, int key  ){		
		int left =0;
		int right = array.length-1;
		
		while (left <=right ){			
			int middle = (left + right)/2;
			if (array[middle] == key) return middle;			
			//如果[middle ....right]有序
			if (array[middle] <=array[right]){				
				//如果[middle ....right]有序并且 key 在[middle ....right]中
				if (array[middle] < key && key <= array[right]){					
					left = middle + 1;
				}else{					
					right = middle - 1;
				}
			}else{//如果[left ....middle]有序并且 key 在[left ....middle]中	
				
				if (key < array[middle] && array[left] <= key){
						right =  middle -1;
				}else{
					left = middle + 1;
				}					
			}
		}
				
		return -1;				
	}		
}