// See longunstr.py for details.
#include <stdio.h>
#include <stdint.h>
#include <string.h>

typedef struct {
  char *s;
  size_t n;
} str;

typedef uint8_t u8;

// XXX note: byte case only
// This is arguably a bit cleaner than the Python.
str
longunstr(str s)
{
  size_t pos[256] = {0}, i = 0, j, n = 0, m = 0;

  for (j = 0; j < s.n; j++) {
    u8 c = s.s[j];
    if (pos[c] > i) i = pos[c];
    pos[c] = j + 1;
    if (j+1 - i > m - n) n = i, m = j+1;
  }

  return (str){ .s = s.s + n, .n = m - n };
}

// size_t pos[256] = {0}, i = 0, j, n = 0, m = 0; for (j = 0; j < s.n; j++) {u8 c = s.s[j]; if (pos[c] > i) {i = pos[c];} pos[c] = j + 1; if (j+1 - i > m - n) {n = i; m = j+1;}} return (str){ .s = s.s + n, .n = m - n };

void
strite(FILE *f, str s)
{
  fwrite(s.s, 1, s.n, f);
}

int
main(int argc, char **argv)
{
  if (argc != 2) {
    fprintf(stderr, "Usage: %s XabcXYdefY\n"
            "Print longest substring of XabcXYdefY without repeated bytes.\n",
            argv[0]);
    return -1;
  }

  printf("longunstr(%s) = ", argv[1]);
  strite(stdout, longunstr((str){ .s = argv[1], .n = strlen(argv[1]) }));
  printf("\n");
  return 0;
}