Kotlin递归结构

fun factorial(n: Int): Int {
    // 基本情况
    if (n == 0) return 1
    // 递归步骤
    return n * factorial(n - 1)
}

fun main() {
    println(factorial(5))  // 输出: 120
}

tailrec fun factorialTailRec(n: Int, accumulator: Int = 1): Int {
    return if (n == 0) accumulator else factorialTailRec(n - 1, n * accumulator)
}

fun main() {
    println(factorialTailRec(5))  // 输出: 120
}

val memo = mutableMapOf<Int, Int>()

fun factorialMemo(n: Int): Int {
    if (n == 0) return 1
    if (memo.containsKey(n)) return memo[n]!!
    val result = n * factorialMemo(n - 1)
    memo[n] = result
    return result
}

fun main() {
    println(factorialMemo(5))  // 输出: 120
}