What is the output of calling compute(4)?
#include <stdio.h>
int compute(int n) {
if (n <= 1) return 1;
return n * compute(n - 2);
}
int main(void) {
printf("%d", compute(4));
return 0;
}compute(4) = 4 * compute(2) = 4 * 2 * compute(0) = 4 * 2 * 1 = 8 (calculates double factorial 4!!).
What does the following function return for is_palindrome("radar", 0, 4)?
int is_palindrome(char *s, int l, int r) {
if (l >= r) return 1;
if (s[l] != s[r]) return 0;
return is_palindrome(s, l + 1, r - 1);
}Checks if string 'radar' is a palindrome recursively, returning 1 (true).
What will be the output of the following C code?
#include <stdio.h>
int f(int n) {
if (n <= 0) return 0;
return (n % 10 == 0) + f(n / 10);
}
int main(void) {
printf("%d", f(102030));
return 0;
}Counts the number of zero digits in 102030, which is 3.
Which sorting algorithm heavily relies on recursive divide and conquer?
Merge sort divides arrays into sub-arrays recursively.
What is the output of the C function below for func(3)?
#include <stdio.h>
void func(int n) {
static int d = 1;
printf("%d %d ", n, d);
d++;
if (n > 1) func(n - 1);
printf("%d %d ", n, d);
}Tracing static d across calls: n=3 d=1; n=2 d=2; n=1 d=3. On return, prints n with d=4.