import Foundation
/// Finds the digit that comes before the target digit when scanning from right to left.
/// Returns: The digit that comes before the target, or -1 if not found or no previous digit.
func findPreviousDigit(in number: Int, target: Int) -> Int {
var num = number
while num > 0 {
let current = num % 10
num /= 10
if current == target {
return num > 0 ? num % 10 : -1
}
}
return -1
}
let number = 8902741
let target = 7
let result = findPreviousDigit(in: number, target: target)
if result != -1 {
print("The digit before \(target) in \(number) is \(result).")
} else {
print("The digit \(target) is not found or has no previous digit in \(number).")
}
/*
run:
The digit before 7 in 8902741 is 2.
*/
