https://www.acmicpc.net/problem/2444
import java.util.*;
fun main(args: Array<String>) {
val s=Scanner(System.`in`)
var n=s.nextInt()
for(i in 1..n){
for(j in 0 until n-i) print(" ");
for(j in 0 until (i-1)*2+1) print("*")
println()
}
for(i in n-1 downTo 1){
for(j in 0 until n-i) print(" ");
for(j in 0 until (i-1)*2+1) print("*")
println()
}
}