Returning a new array created from adding odd numbers from an array-CodePudding

I am trying to create an array from this following array arr=[1,2,3,4,5,6,7,8,9] and it will return as sum of numbers in this way 1 3 =4 ,3 5=8,5 7=12,7 9=16. so that final answer would be newArray =[4,8,12,16]. How can I achieve it. I have done below code but it doesn't work .

   fun main(){

    val sum = arrayOf(1,2,3,4,5,6,7,8,9)
    var first =0;
    var second=0

    for (i in sum.indices){
        if(sum[i]%2!=0){
            first  = sum[i]
            if (second!=0){
                println(" $first   $second")
                first=second
            }
        }
    }


}

CodePudding user response：

// val arr = arrayOf(1, 2, 3, 4, 5, 6, 7, 8, 9)
val arr = arrayOf(1, 3, 5, 6, 7, 8, 2, 4, 9)   // shuffled for test purposes

val result = arr
  // I first posted this line, which was wrong:
  // .filterIndexed { index, _ -> index % 2 == 0 }
  .filterIndexed { _, value -> value % 2 == 1 }
  .windowed(2, 1)
  .map { it.sum() }

println(result)

Details of the three steps:

After filterIndexed: [1, 3, 5, 7, 9]
After windowed: [[1, 3], [3, 5], [5, 7], [7, 9]]
And in the map each sublist is summed up.

Edit: The first version of this answer with filtering for index % 2 == 0 does by coincidence lead to the same result, because the input array in the OP was not shuffled.

CodePudding user response：

lukas.j's answer is superior, but I wanted to also show a solution with only slight changes to your own code:

val sum = arrayOf(1,2,3,4,5,6,7,8,9)
var first =0;
var second=0
var result = emptyArray<Int>()
for (i in sum.indices){
    if(sum[i]%2!=0){

        if (first == 0) first = sum[i]
        else second = sum[i]

        if (second!=0){
            println(" $first   $second")
            result  = first   second
            first=second
        }
    }
}
println(result.contentToString())