What is the return value of power_mod(2, 10, 1000)?
int power_mod(int b, int e, int m) {
if (e == 0) return 1;
long long t = power_mod(b, e / 2, m);
t = (t * t) % m;
if (e % 2 != 0) t = (t * b) % m;
return t;
}$2^10$ = 1024; 1024 % 1000 = 24.
How many call stack frames are active right before the base case returns in factorial(4)?
Stack frames for factorial(4), factorial(3), factorial(2), factorial(1), and factorial(0) = 5 frames.
What is the output of calling print_num(12)?
#include <stdio.h>
void print_num(int n) {
if (n == 0) return;
print_num(n / 2);
printf("%d", n % 2);
}12 in binary is 1100_2.
What is the output of the following C code?
#include <stdio.h>
int f(int a, int b) {
if (b == 0) return 0;
if (b == 1) return a;
return a + f(a, b - 1);
}
int main(void) {
printf("%d", f(6, 4));
return 0;
}f(6, 4) calculates 6 * 4 = 24 via repeated addition.
What will be the output of the following code?
#include <stdio.h>
int run(int n) {
if (n <= 1) return 1;
return run(n - 1) + run(n - 2);
}
int main(void) {
printf("%d", run(5));
return 0;
}Fibonacci sequence: run(1)=1, run(2)=2, run(3)=3, run(4)=5, run(5)=8.