Problem Explanation: Given two arrays A and B of equal length N, write a function that returns an array C of length N where C[i] represents the number of occurrences of A[i] in array B.
Example:
Input: A = [1, 2, 3, 4, 5], B = [1, 1, 2, 2, 1]
Output: C = [3, 2, 0, 0, 0]Input: A = [10, 20, 30, 40, 50], B = [50, 40, 30, 20, 10]
Output: C = [1, 1, 1, 1, 1]Expected Time and Space Complexity: O(N) time complexity and O(N) space complexity,
where N is the length of the input arrays A and B.
Constraints:
- The length of input arrays A and B will be equal and at most 10^5.
- The elements of the input arrays A and B will be integers between 1 and 10^9, inclusive.
Kotlin Solution :
Kotlin
fun elementFrequencyCounter(A: IntArray, B: IntArray): IntArray {
val map = mutableMapOf<Int, Int>()
for (b in B) {
map[b] = map.getOrDefault(b, 0) + 1
}
val C = IntArray(A.size)
for (i in A.indices) {
C[i] = map.getOrDefault(A[i], 0)
}
return C
}
fun main() {
val A = intArrayOf(1, 2, 3, 4, 5)
val B = intArrayOf(1, 1, 2, 2, 1)
val C = elementFrequencyCounter(A, B)
println(C.contentToString())
// Output: [3, 2, 0, 0, 0]
val D = intArrayOf(10, 20, 30, 40, 50)
val E = intArrayOf(50, 40, 30, 20, 10)
val F = elementFrequencyCounter(D, E)
println(F.contentToString())
// Output: [1, 1, 1, 1, 1]
}