gistfile1.h

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>

enum dir {North, West, East, South, NONE};

unsigned int look_alt(int h, int w, int H, int W, enum dir dir, unsigned int *alt_map) {
#define ALT(m,n) *(alt_map + (m) * W + (n))
  if (dir == North) {
    if (h == 0)
      return UINT_MAX;
    else
      return ALT(h - 1, w);
  }   
  if (dir == West) {
    if (w == 0)
      return UINT_MAX;
    else
      return ALT(h, w - 1);
  }   
  if (dir == East) {
    if (w + 1 >= W)
      return UINT_MAX;
    else
      return ALT(h, w + 1);
  }   
  if (dir == South) {
    if(h + 1 >= H)
      return UINT_MAX;
    else
      return ALT(h+1, w);
  }   
} 

enum dir water (int h, int w, int H, int W, unsigned int * alt_map) {
  unsigned int min_alt = *(alt_map + h * W + w);
  unsigned int cand_alt;
  enum dir min_dir = NONE;
  enum dir cand_dir;

  cand_dir = North;
  if ((cand_alt = look_alt(h, w, H, W, cand_dir, alt_map)) < min_alt) {
    min_alt = cand_alt;
    min_dir = cand_dir;
  }
  cand_dir = West;
  if ((cand_alt = look_alt(h, w, H, W, cand_dir, alt_map)) < min_alt) {
    min_alt = cand_alt;
    min_dir = cand_dir;
  }
  cand_dir = East;
  if ((cand_alt = look_alt(h, w, H, W, cand_dir, alt_map)) < min_alt) {
    min_alt = cand_alt;
    min_dir = cand_dir;
  }
  cand_dir = South;
  if ((cand_alt = look_alt(h, w, H, W, cand_dir, alt_map)) < min_alt) {
    min_alt = cand_alt;
    min_dir = cand_dir;
  }

  return min_dir;
}

char follow(int h, int w, int H, int W,
            unsigned int *alt_map, char* result_map, char* next_letter)
{ 
  enum dir next = water(h, w, H, W, alt_map);
  char ret;
  char* result = result_map + h * W + w;

  if (*result)
    return *result;

  switch(next) {
  case NONE:
    /* is basin */
    *result = *next_letter;
    (*next_letter) ++;
    return *result;
  case North:
    ret = follow(h - 1, w, H, W, alt_map, result_map, next_letter);
    break;
  case West:
    ret = follow(h, w - 1, H, W, alt_map, result_map, next_letter);
    break;
  case East:
    ret = follow(h, w + 1, H, W, alt_map, result_map, next_letter);
    break;
  case South:
    break;
  }
  *result = ret;
  return ret;
}


void main(void) {
  int T;
  int t;
  scanf("%d\n", &T);

  for (t = 0; t < T; t++) {
    int H, W;
    int h, w;
    unsigned int * alt_map;
    char next_letter;
    char * result_map;

    next_letter = 'a';
    scanf("%d %d\n", &H, &W);
    alt_map = calloc(sizeof(unsigned int), H * W);
    result_map = calloc(sizeof(char), H * W);
    for (h = 0; h < H; h++) {
      for (w = 0; w < W; w++)
        scanf("%d ", alt_map + h * W + w);
    }

    for (h = 0; h < H; h++) {
      for (w = 0; w < W; w++) {
        follow(h, w, H, W, alt_map, result_map, &next_letter);
      }
    }

    free(alt_map);

    printf("Case #%d:\n", t + 1);

    for (h = 0; h < H; h++) {
      for (w = 0; w < W; w++) {
        printf("%c", *(result_map + h * W + w));
        if (w + 1 == W)
          printf("\n");
        else
          printf(" ");
      }
    }

    free(result_map);
  }
}