LeetCode

package LeetCode.contact;
//二分查找
class Solution_704 {
    public int search(int[] nums, int target) {
    	
    	int start = 0;
    	int end = nums.length-1;
    	//使用二分法最多查找次数为(nums.length/2)+ 1
    	for(int i =0; i<(int)(nums.length/2 + 1);i++){
    		int middle = (int)((end - start +1)  /2) + start;
    		if(nums[middle] == target){
    			return middle;
    		}else if(nums[middle] >  target){
    			end = middle-1;		//注意返回的值并不是middle
    			//越界判断，一旦越界返回-1
    			while(end <0 || end >nums.length-1){return -1;}
    		}else{
    			start = middle+1;
    			//越界判断，一旦越界返回-1
    			while(start <0 || start >nums.length-1){return -1;}
    		}
    	}
    	return -1;
    }
}

public class leetcode_704 {
	public static void main(String[] args){
		int[] arr = new int[]{-1,0,3,5,9,12};
		Solution_704 sol = new Solution_704();
		int a = sol.search(arr, 13);
		System.out.println(a);
	}
}