LeetCode704 Binary Search

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博客给出一个LeetCode题目，要求在升序整数数组中查找目标值。若目标值存在则返回其索引，不存在则返回 -1，并给出两个示例，分别展示目标值存在和不存在的情况。

题目：

Given a sorted (in ascending order) integer array nums of n elements and a target value, write a function to search target in nums. If target exists, then return its index, otherwise return -1.

Example 1:

Input: nums = [-1,0,3,5,9,12], target = 9

Output: 4

Explanation: 9 exists in nums and its index is 4

Example 2:

Input: nums = [-1,0,3,5,9,12], target = 2

Output: -1

Explanation: 2 does not exist in nums so return -1

public class BinarySearch {
    public static int search(int[] nums, int target) {
        //处理特殊例子
        //数组为null或者数组为空
        if(nums == null || nums.length == 0)
            return -1;

        //实现业务逻辑
        int l = 0;
        int r = nums.length - 1;

        while(l <= r){
            int mid = l + (r - l >> 1);
            if(nums[mid] == target)
                return mid;
            if(target > nums[mid])
                l = mid + 1;
            else
                r = mid - 1;
        }

        return -1;
    }

    public static void main(String[] args) {
        int[] nums = {-1,0,3,5,9,12};
        int target = 9;
        System.out.println(search(nums, target));
    }
}