Binary Search Example with Labeled IndicesBinary Search Example with Labeled Indices

-9 -2 -1 0 3 5 7 17 25

yellow == low

-9 -2 -1 0 3 5 7 17 25

Compare key to middle element…

-9 -2 -1 0 3 5 7 17 25

It can’t be in the first half; eliminate first half and compare to middle of what remains

-9 -2 -1 0 3 5 7 17 25

-9 -2 -1 0 3 5 7 17 -9

Can’t be 7 or anything greater; eliminate those elements and compare again

-9 -2 -1 0 3 5 7 17 -95 is now the only thing remaining in the array. It is thus also the middle. Since the middle equals the key, we’ve successfully found our key.

blue == highgreen == middle

1 2 3 4 5 6 7 8 9