#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <assert.h>
#include <string.h>


/*
Implement an algorithm to determine if a string has all unique
characters.  What if you can not use additional data structures?
*/

bool nodup(char * s){
  int chars[256] = {0};
  int len = strlen(s);

  printf("s = %s\n", s);

  int val;
  for (int i = 0; i < len; i++){
    val = s[i];
    printf("%c = %d\n", s[i], val);
    if (chars[val]) return false;
    chars[val]++;
  }
  return true;
}

bool nodup2(char * s){
  int len = strlen(s);

  printf("s = %s\n", s);

  int val;
  for (int i = 0; i < len; i++){
    val = s[i];
    printf("%c = %d\n", s[i], val);
    for (int j = i; j < len; j++){
      if (s[j] == val) return false;
    }
  }
  return true;
}

/*
  Write code to reverse a C-Style String. (C-String means that “abcd”
is represented as five characters, including the null character.)
*/


void reverse(char * str){
  char * end = str;
  char tmp;

  if (str) {
    while (*end) {
      ++end;
    }
    --end;
    while (str < end) {
      tmp = *str;
      *str++ = *end;
      *end-- = tmp;
    }
  }
}

/*
Design an algorithm and write code to remove the duplicate characters
in a string without using any additional buffer. NOTE: One or two
additional variables are fine.  An extra copy of the array is not.
*/

char * dedup(char * str){

  char tmp;
  int len = strlen(str);

  for (int i = 0; i < len; i++) {
    tmp = str[i];
    for (int j = i; j < len; j++){
      if (str[j] == tmp) {
	len--;
	for (int k = j; k < len; k++){
	  str[k] = str[k+1];
	}
      }
    }
  }
}


int main(int argc, char ** argv){

  if (argc < 2) {
    fprintf(stderr, "Usage: %s string+\n", argv[0]);
    exit(1);
  }

  for (int i = 1; i< argc; i++) {

    printf("String: %s has %s\n", argv[i], (nodup(argv[i])) ? " no dups" : " some dups");
    printf("String: %s has %s\n", argv[i], (nodup2(argv[i])) ? " no dups" : " some dups");
    printf("Reverse of %s == ", argv[i]);
    reverse(argv[i]);
    printf(" %s\n", argv[i]);
    printf("Dedup of %s == ", argv[i]);
    dedup(argv[i]);
    printf(" %s\n", argv[i]);
  }
  
}