二分查找有序数组中的特定值

1、题目背景

给定一个n个元素有序的（升序）整型数组nums和一个目标值target写一个函数搜索nums中的target,如果目标值存在返回下标,否则返回-1

2、代码实现

public class Solution {

    public static void main(String[] args) {

        int[] nums = new int[]{-2, 1, -3, 4, -1, 2, 1, -5, 4};
        System.out.println(search(nums, 1));
    }

    /**
     * 给定一个n个元素有序的（升序）整型数组nums和一个目标值target
     * 写一个函数搜索nums中的target,如果目标值存在返回下标,否则返回-1
     * @param nums
     * @param target
     * @return
     */
    public static int search(int[] nums, int target) {

        if (target < nums[0] || target > nums[nums.length - 1]) {
            return -1;
        }
        int left = 0, right = nums.length - 1;
        while (left <= right) {
            int mid = left + ((right - left) >> 1);
            if (nums[mid] == target)
                return mid;
            else if (nums[mid] < target)
                left = mid + 1;
            else if (nums[mid] > target)
                right = mid - 1;
        }
        return -1;
    }
}

3、结果展示

6
Process finished with exit code 0