binarySearch while 写法

//Given an array of integers nums which is sorted in ascending order,
// and an integer target, write a function to search target in nums.
// If target exists, then return its index. Otherwise, return -1.
//
//You must write an algorithm with O(log n) runtime complexity

public class Solution {
    public int search(int[] nums, int target) {
        int l = -1;
        int r = nums.length;
        int mid;
        // 二分查找大于等于 target 值的最小下标
        while (r - l > 1) {
            mid = (l + r) / 2;
            if (nums[mid] >= target) {
                r = mid;
            } else {
                l = mid;
            }
        }
        // 下表超尾或者下表的值不等于 target 就说明不存在
        if (r >= nums.length || nums[r] != target) {
            return -1;
        }
        return r;
    }
}