beads.cpp

/*
ID: dvyjone1
PROG: beads
LANG: C++
*/
#include <iostream>
#include <fstream>
#include <string>

typedef struct bead {
  struct bead *previous;
  char color;
  struct bead *next;
} Bead;

typedef struct bead *BeadPtr;

int count_beads(BeadPtr first_bead, char color, int max, int backwards) {
  int i;
  BeadPtr current_bead = first_bead;
  for (i = 0; i < max; ++i) {
    if (current_bead->color == color || current_bead->color == 'w') {
      if (backwards) {
        current_bead = current_bead->previous;
      } else {
        current_bead = current_bead->next;
      }
    } else {
      break;
    }
  }

  return i;
}

char find_color(BeadPtr bead, int backwards, int max) {
  if (max == 0) return bead->color;
  if (bead->color == 'r' || bead->color == 'b') return bead->color;
  if (backwards) return find_color(bead->previous, backwards, --max);
  else return find_color(bead->next, backwards, --max);
}

int main() {
  std::ofstream fout ("beads.out");
  std::ifstream fin ("beads.in");

  int N, i;
  fin >> N;

  BeadPtr beads = (BeadPtr)calloc(N, sizeof(Bead));

  for (i = 0; i < N; ++i) {
    fin >> beads[i].color;

    if (i == 0) {
      beads[i].previous = beads + N-1;
      beads[i].next = beads + 1;
    } else if (i == N-1) {
      beads[i].previous = beads + N - 2;
      beads[i].next = beads;
    } else {
      beads[i].previous = beads + i - 1;
      beads[i].next = beads + i + 1;
    }
  }

  int max = 0;

  for (i = 0; i < N; ++i) {
    int j = 0, bead_count = 0;
    BeadPtr current_bead = beads + i;

    bead_count = count_beads(current_bead, find_color(current_bead, 0, N), N, 0);
    bead_count += count_beads(current_bead->previous, find_color(current_bead->previous, 1, N), N, 1);

    std::cout << i << "\t" << bead_count << "\t" << current_bead->color << "\t" << current_bead->previous->color << std::endl;

    if (bead_count > max) max = bead_count;
  }

  if (max > N) max = N;

  fout << max << std::endl;

  return 0;
}