nen thingy

#include <stdio.h>
#include <string.h>

void assertEquals(char*, char*);
char* reverse(char*);
char* reverse_helper(char* s, int, int);

// clang -o out main.c && ./out
int main() {
  assertEquals("", reverse(""));
  assertEquals("a", reverse("a"));

  char in[] = "ab";
  char out[] = "ba";
  assertEquals(out, reverse(in));

  char in2[] = "cba";
  char out2[] = "abc";
  assertEquals(out2, reverse(in2));

  return 0;
}

char* reverse(char* s) {
  return reverse_helper(s, 0, strlen(s) - 1);
}

char* reverse_helper(char* s, int curr, int end) {
  if (curr == end || end < curr) {
    return s;
  }

  char temp = s[curr];
  s[curr] = s[end];
  s[end] = temp;
  return reverse_helper(s, curr + 1, end - 1);
}

void assertEquals(char* s1, char* s2) {
  if (strcmp(s1, s2) != 0) {
    printf("FAIL: Expected '%s', Actual '%s'\n", s1, s2);
  } else {
    printf("SUCC: Expected '%s', Actual '%s'\n", s1, s2);
  }
}