二分查找法

public class Solution{
    public int search(int[] nums, int target){
        int start = 0;
        int end = nums.length - 1;
        while(start <= end){
            int middle = (start + end)/2;
            if(nums[middle]==target){
                return middle;
            }else if(nums[middle]>=target){
                end = middle -1 ;
            }else{
                start = middle + 1；
            }
        }
        return -1;
    }    
}