Algorithm

The starting boundary is at the beginning of the array, and the ending boundary is at the last position. This is because the entire array is our search area. In each step, we adjust these boundaries to narrow down the area until we find the target number or confirm it is not present.
First, we find the middle position of the current search area and check if the number at this position is the target.
- If it is the target, we stop searching.
- If the target is larger than the middle number, we only need to search the right half, so we move the starting boundary to just after the middle.
- If the target is smaller than the middle number, we only need to search the left half, so we move the ending boundary to just before the middle.
- The search stops when the starting boundary crosses the ending boundary, meaning there is no space left to search.

This searching applies only when the array is sorted.

Dry Run