Đệ quy

1calls = 02
3def fib(n, depth=0):4    global calls5    calls += 16    # Print the call with its depth so the recursion is visible7    print("  " * depth + f"fib({n})")8    if n <= 1:9        return n10    return fib(n - 1, depth + 1) + fib(n - 2, depth + 1)11
12
13print("fib(5) =", fib(5))14print("calls made:", calls)

1let calls = 0;2
3function fib(n, depth = 0) {4    calls += 1;5    // Print the call with its depth so the recursion is visible6    console.log('  '.repeat(depth) + `fib(${n})`);7    if (n <= 1) return n;8    return fib(n - 1, depth + 1) + fib(n - 2, depth + 1);9}10
11console.log('fib(5) =', fib(5));12console.log('calls made:', calls);

1public class Main {2    static int calls = 0;3
4    static int fib(int n, int depth) {5        calls++;6        // Print the call with its depth so the recursion is visible7        System.out.println("  ".repeat(depth) + "fib(" + n + ")");8        if (n <= 1) return n;9        return fib(n - 1, depth + 1) + fib(n - 2, depth + 1);10    }11
12    public static void main(String[] args) {13        System.out.println("fib(5) = " + fib(5, 0));14        System.out.println("calls made: " + calls);15    }16}

1#include <iostream>2#include <string>3
4int calls = 0;5
6int fib(int n, int depth) {7    calls++;8    // Print the call with its depth so the recursion is visible9    std::cout << std::string(depth * 2, ' ') << "fib(" << n << ")\n";10    if (n <= 1) return n;11    return fib(n - 1, depth + 1) + fib(n - 2, depth + 1);12}13
14int main() {15    int result = fib(5, 0);16    std::cout << "fib(5) = " << result << "\n";17    std::cout << "calls made: " << calls << "\n";18    return 0;19}

1#include <stdio.h>2
3int calls = 0;4
5int fib(int n, int depth) {6    calls++;7    /* Print the call with its depth so the recursion is visible */8    printf("%*sfib(%d)\n", depth * 2, "", n);9    if (n <= 1) return n;10    return fib(n - 1, depth + 1) + fib(n - 2, depth + 1);11}12
13int main(void) {14    printf("fib(5) = %d\n", fib(5, 0));15    printf("calls made: %d\n", calls);16    return 0;17}