# 704. Binary Search

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.

### Thoughts

* I mean, this is just a binary search....... idk that I have many other thoughts on this :sob:
    

### Solution

```java
class Solution {
    public int search(int[] nums, int target) {
        // Declare variables
        int h = nums.length - 1, l = 0;
        
        while (l <= h) {
            // Calculate the midpoint given the previous highs and lows
            int curIndex = ((h - l) / 2) + l;

            if (nums[curIndex] == target) {
                return curIndex;
            }

            // Set the highs and lows, excludes half of the data at a time for each iteration
            if (nums[curIndex] > target) {
                h = curIndex - 1;
            } else {
                l = curIndex + 1;
            }
        }

        return -1;
    }
}
```

**Time Complexity:** O(log n)  
**Space Complexity:** O(1)

### Conclusion

This one took me embarrassingly long to get. It has been a long time since I have had to use binary search, so it took me a while to remember how to do it. (Clearly I should've done more thinking about the question before I actually started!) Now that I have refreshed on it though, I feel way better about my understanding of it now, so perhaps this wasn't a complete wash.