package main
import (
"fmt"
)
// FindPreviousDigit returns the digit that comes before the target digit
// when scanning the number from right to left.
// If the target is not found or has no previous digit, it returns -1.
func FindPreviousDigit(number, target int) int {
for number > 0 {
current := number % 10
number /= 10
if current == target {
if number > 0 {
return number % 10
}
return -1
}
}
return -1
}
func main() {
number := 8902741
target := 7
result := FindPreviousDigit(number, target)
if result != -1 {
fmt.Printf("The digit before %d in %d is %d.\n", target, number, result)
} else {
fmt.Printf("The digit %d is not found or has no previous digit in %d.\n", target, number)
}
}
/*
run:
The digit before 7 in 8902741 is 2.
*/
