Replacing an element in Kotlin 2D list - kotlin

Question

I'm trying to replace an element in 2D list
hand instead of one element at one specified index all element are changing
this is the list
`private val printS: MutableList<MutableList<Char>> = mutableListOf(mutableListOf())`
This is how I literate them
// adding S to the list
for (i in 1..seat) printS[0].add('S')
// now we have list of S char in the printS list
for (i in 1..row) {
printS.add(printS[0])
}
now try to change list 5 element 5
printS[5][5] = 'B'
this is the result
1 2 3 4 5 6 7
1 S S S S S B S
2 S S S S S B S
3 S S S S S B S
4 S S S S S B S
5 S S S S S B S
6 S S S S S B S
7 S S S S S B S
all the lists have changed not just one
I need to just change one Char so the result should be
1 2 3 4 5 6 7
1 S S S S S S S
2 S S S S S S S
3 S S S S S S S
4 S S S S S S S
5 S S S S S S S
6 S S S S S B S
7 S S S S S S S

Answer 1

Edit (based on OP's clarification in the first comment below):
val rows = 7
val cols = 7
val result = MutableList(rows) { MutableList(cols) { 'S' } }
result[5][5] = 'B'
Still valid:
Your code does not work because the inner loop is not nested due to you not having put parentheses on the outer loop:
for (i in 1..seat) printS[0].add('S')
for (i in 1..row) {
printS.add(printS[0])
}
This means – properly formatted - nothing else than:
for (i in 1..seat) {
printS[0].add('S')
}
for (i in 1..row) {
printS.add(printS[0])
}
Obsolete:
This should work:
val rows = 7
val cols = 7
val result: MutableList<MutableList<Char>> = mutableListOf()
for (row in 0 until rows) {
result.add(mutableListOf())
for (col in 0 until rows) {
result[row].add(if (row = 5 && col == 5) 'B' else 'S')
}
}
result.forEach(::println)
Output:
[S, S, S, S, S, S, S]
[S, S, S, S, S, S, S]
[S, S, S, S, S, S, S]
[S, S, S, S, S, S, S]
[S, S, S, S, S, S, S]
[S, S, S, S, S, B, S]
[S, S, S, S, S, S, S]
But a shorter way to create this matrix would be:
val result = List(rows) { row ->
List(cols) { col ->
if (row == 5 && col == 5) 'B' else 'S'
}
}