I have this code:
if ((oldTest != null) && (oldTest.snapshotUrl != null)) {
val startPos = oldTest.snapshotUrl!!.lastIndexOf("_") + 1
}
Is there a way in Kotlin to shorten this? I don't believe it's necessary to check to see if oldTest.snapshotUrl is null. Unfortunately this does not work:
if (oldTest != null) {
val startPos = oldTest.snapshotUrl?.lastIndexOf("_") + 1
}
oldTest?.snapshotUrl?.let {
val startPos = it.lastIndexOf("_") + 1
}
See https://kotlinlang.org/docs/reference/idioms.html#execute-if-not-null
Or, if snapshotUrl is not nullable
oldTest?.let {
val startPos = it.snapshotUrl.lastIndexOf("_") + 1
}
Related
I can't solve this problem, how to separate the numbers and do the required arithmetic
https://codeforces.com/group/MWSDmqGsZm/contest/219158/problem/O
This is my code , I don't know how true it is
fun main(args:Array<String>) {
val scanner = Scanner(System.`in`)
var s: String = read()!!
var c: Char? = null
var a: String = ""
var b: String = ""
var t: Boolean = true
for (i in 1..s.length) {
if (s[i] == '+' || s[i] == '-' || s[i] == '*' || s[i] == '/') {
c = s[i]
t = false
}else{
if(t){
a+=s[i]
}else{
b+=s[i]
}
}
}
if(c=='+'){
println(a+b)
}else if (c=='-'){
println( "$a - $b" )
}else if (c=='*'){
println("$a * $b")
}else{
println("$a / $b")
}
Try this code:
fun main() {
val str = readLine()!!
val (index, operator) = str.findAnyOf(listOf("+", "-", "*", "/"))!!
val a = str.substring(0, index).toInt()
val b = str.substring(index + 1).toInt()
val result = when (operator) {
"+" -> a + b
"-" -> a - b
"*" -> a * b
"/" -> a / b
else -> -1
}
println(result)
}
findAnyOf documentation:
Finds the first occurrence of any of the specified [strings] in this char sequence.
Returns A pair of an index of the first occurrence of matched string from [strings] and the string matched or null if none of [strings] are found.
Rest of the logic is quite straightforward.
How to compare each char from the String with Keys from the HashMap?
I have used loops of course and change each Key to Char.
val romanNumbers = HashMap<String, Int>()
romanNumbers[""] = 0
romanNumbers["I"] = 1
romanNumbers["V"] = 5
Instead of string.get(i) I also tried string[i]
for (i in string.indices){
for ((k, v) in romanNumbers) {
if (string.length == 1) {
res1 = romanNumbers.getValue(string)
}
if (string.get(i) == k.single()) {
num1 = v
}
if (string[i + 1] == k.single()) {
num2 = v
}
}
}
error
Exception in thread "main" java.util.NoSuchElementException: Char sequence is empty.
at kotlin.text.StringsKt___StringsKt.single(_Strings.kt:223)
at CodeWars.MappingTrainingKt.decode(MappingTraining.kt:38)
at CodeWars.MappingTrainingKt.main(MappingTraining.kt:4)
at CodeWars.MappingTrainingKt.main(MappingTraining.kt)
An error occurred while using the ConverPrice function as follows for information about the price.
The price of the item in the recycler view adapter onBindViewHolder.
As a result of debugging, the error occurs in the following code.
priceText =
"${dec.format(priceMin)} ~ ${dec.format(priceMax)}"
Please check my code and answer.
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
when (holder) {
is DataViewHolder -> {
val item = dataList[position]
item.price.let {
holder.price.text = ConvertPrice(item, holder.price)
}
}
}
}
fun ConvertPrice(productDetail: ProductDetail?, tv: TextView? = null, setPrice: Boolean = false): String {
val disableColor = Color.parseColor("#aaaaaa")
val enableColor = Color.parseColor("#3692ff")
tv?.setTextColor(disableColor)
if (ProductDetail != null) {
val priceMin = productDetail.priceMin
val priceMax = productDetail.priceMax
var priceText = ""
val dec = DecimalFormat("##,###")
productDetail.enabledRetail?.let {
if (productDetail.enabledRetail == true) {
if (setPrice) {
priceText = if (priceMin == null || priceMax == null) {
"No pricing information"
} else {
"${dec.format(priceMin)} ~ ${dec.format(priceMax)}"
}
tv?.setTextColor(disableColor)
}
else {
priceText = dec.format(wineDetail.price).toString()
tv?.setTextColor(enableColor)
}
return priceText
} else if (productDetail.cntRating!! > 0) {
if ((priceMin == null && priceMax == null) || (priceMin == 0 && priceMax == 0)) {
priceText = "No pricing information"
} else {
priceText =
"${dec.format(priceMin)} ~ ${dec.format(priceMax)}"
tv?.setTextColor(disableColor)
}
return priceText
}
}
}
return "No pricing information"
}
DecimalFormat.format() only works fine with long or double. You should convert "priceMin" and "priceMax" to Long.
val priceMin = productDetail.priceMin.toLong()
val priceMax = productDetail.priceMax.toLong()
I recommend to use NumberFormat instead of DecimalFormat because it is locale-sensitive
val decFormat = NumberFormat.getInstance() // or getCurrencyInstance()
decFormat.maximumFractionDigits = 3
decFormat.format(priceMin)
decFormat.format(priceMax)
The program works, however, I still get a logical error: the final letter doesn't run through. For example, when I enter aaaabbbbccccdddd the output I get is a4b4c4 but there is no d4.
fun main () {
val strUser = readLine()!!.toLowerCase()
val iLength = strUser!!.length
var iMatch : Int = 0
var chrMatch : Char = strUser[0]
for (i in 0..iLength) {
if (strUser[i] == chrMatch) {
iMatch += 1
}else {
print("$chrMatch$iMatch")
chrMatch = strUser[i]
iMatch = 1
}
}
}
There are many solutions, but the best is RegExp
fun encode(input: String): String =
input.replace(Regex("(.)\\1*")) {
String.format("%d%s", it.value.length, it.groupValues[1])
}
demo
Test result
println(encode("aaaabbbbccccdddd")) // 4a4b4c4d
strUser contains chars by indexes from 0 to iLength - 1 so you have to write for (i in 0 until iLength) instead of for (i in 0..iLength)
But Tenfour04 is completely right, you can just iterate strUser without indexes:
fun main() {
val strUser = readLine()!!.toLowerCase()
var iMatch: Int = 0
var chrMatch: Char = strUser[0]
for (char in strUser) {
if (char == chrMatch) {
iMatch += 1
} else {
print("$chrMatch$iMatch")
chrMatch = char
iMatch = 1
}
}
}
fun main () {
val strUser = readLine()!!.toLowerCase()
var iMatch : Int = 0
var chrMatch : Char = strUser[0]
for (char in strUser+1) {
if (char == chrMatch) {
iMatch += 1
}else {
print("$chrMatch$iMatch")
chrMatch = char
iMatch = 1
}
}
}
fun runLengthEncoding(inputString: String): String {
val n=inputString.length
var i : Int =0
var result : String =""
while(i<n){
var count =1
while(i<n-1 && inputString[i] == inputString[i+1]){
count ++
i++
}
result=result.toString()+count.toString()+inputString[i].toString()
i++
}
return result
}
Im trying to do this exercise
https://www.hackerrank.com/challenges/compare-the-triplets/problem?h_r=next-challenge&h_v=zen
I already wrote the code but the result is not right and for my eyes its all good
Could somebody pls tell me whats wrong??
thx
import java.util.Scanner
fun main(){
var loop = 0
var score = Array<Int>(2){0}
val reader = Scanner(System.`in`)
var alice:String = readLine().toString()
var bob:String = readLine().toString()
val numerosa: List<String> = alice.split(" ")
val numerosb:List<String> = bob.split(" ")
for(a in 3..3) {
when (numerosa[loop].toInt()) {
in numerosb[loop].toInt() + 1..100 -> score[0] += 1
in numerosb[loop].toInt() - 1..0 -> score[1] += 1
}
loop += 1
}
println("${score[0]} ${score[1]}")
}
You could do it something like this, you have multiple variables which were not required so I cleaned up the code.
val score = Array(2) { 0 }
val aliceNumbers = readLine()!!.split(" ").map(String::toInt)
val bobNumbers = readLine()!!.split(" ").map(String::toInt)
require(aliceNumbers.size == 3 && bobNumbers.size == 3) { "There must be 3 numbers for each" }
require(!aliceNumbers.any { it !in 1..100 } || !bobNumbers.any { it !in 1..100 }) { "Numbers must be in range 1 to 100" }
for (a in 0..2) {
if(aliceNumbers[a] > bobNumbers[a]) score[0] += 1
if(aliceNumbers[a] < bobNumbers[a]) score[1] += 1
}
println("${score[0]} ${score[1]}")