Arrays and Iteration

Find Maximum

Scan the array once, keeping the largest value seen so far. The replay highlights when a candidate replaces the running maximum.

Algorithm

Basic Implementation

basic.swift 
let arr = [3, 1, 4, 1, 5, 9, 2, 6]
var best = arr[0]
for i in 1..<arr.count {
	if arr[i] > best {
		best = arr[i]
	}
}
print(best)

Complexity

  • Time: O(n)
  • Space: O(1)

Implementation notes

  • Swift infers arr as an [Int] from let arr = [3, 1, 4, 1, 5, 9, 2, 6]; the let binding means the array is not mutated or rebound.
  • var best = arr[0] seeds the running maximum from the first element, so the loop can start at index 1 without optional or sentinel state.
  • The scan uses for i in 1..<arr.count, visiting indexes 1 through 7 and reading each candidate with arr[i].
  • if arr[i] > best performs a strict Int comparison; equal values do not replace the current maximum.
  • Only best mutates during the loop. The trace records replacements at i=2 (3 -> 4), i=4 (4 -> 5), and i=5 (5 -> 9), with later values leaving best at 9.
  • print(best) writes the final Int as 9.
execution replay The checked-in replay follows the language-neutral state table for `array-find-max`.
cross-language comparison This Swift DSA version keeps the same data and final output as every other DSA book in this wave.