查找算法（1）--二分查找

public int search(int[] arr,int x) throws Exception{
	int start = 0;
	int end = arr.length-1;
	
	while(start<=end){
		int mid = (start+end)/2;
		
		if(arr[mid]>x){
			end = mid-1;
		}else if(arr[mid] == x){
			return mid;
		}else if(arr[mid]<x){
			start = mid+1;
		}
	}
	
	throw new Exception("not found"+x);
}