704. Binary-Search

difficulty: Easy

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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

Note:

1. You may assume that all elements in nums are unique.

2. n will be in the range [1, 10000].

3. The value of each element in nums will be in the range [-9999, 9999].

Method One

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