Binary search is the most incorrectly implemented algorithm in production code. Not because it is hard to understand. Because it is hard to get right.
Jon Bentley tested professional programmers — 90% got binary search wrong when writing it from scratch. Java's Arrays.binarySearch shipped with an overflow bug for nine years. Three lines, three landmines: the loop condition, the midpoint, the pointer update.
Fifteen cells. Sorted. Target = 11. Tap any cell to reveal its value. No pointers, no automation — you choose where to look.