typedef struct QNode{
 int data;
 struct QNode *next;
}QNode;

typedef struct Queue{
 struct QNode* first;
 struct QNode* last;
}Queue;

void PushQueue(Queue *queue, int data){
 QNode *p = NULL;
 p = (QNode*)malloc(sizeof(QNode));
 p->data = data;
 if(queue->first == NULL){
  queue->first = p;
  queue->last = p;
  p->next = NULL;
 }
 else{
  p->next = NULL;
  queue->last->next = p;
  queue->last = p;
 }
}

int PopQueue(Queue *queue){
 QNode *p = NULL;
 int data;
 if(queue->first == NULL){
  return -1;
 }
 p = queue->first;
 data = p->data;
 if(queue->first->next == NULL){
  queue->first = NULL;
  queue->last = NULL;
 }
 else{
  queue->first = p->next;
 }
 free(p);
 return data;
}

static int NeighborDirection[8][2] = {{0,1},{1,1},{1,0},{1,-1},{0,-1},{-1,-1},{-1,0},{-1,1}};

void SearchNeighbor(unsigned char *bitmap, int width, int height, int *labelmap, 
     int labelIndex, int pixelIndex, Queue *queue){
 int searchIndex, i, length;
 labelmap[pixelIndex] = labelIndex;
 length = width * height;
 for(i = 0;i < 8;i++){
  searchIndex = pixelIndex + NeighborDirection[i][0] * width + NeighborDirection[i][1];
  if(searchIndex > 0 && searchIndex < length && 
   bitmap[searchIndex] == 255 && labelmap[searchIndex] == 0){
   labelmap[searchIndex] = labelIndex;
   PushQueue(queue, searchIndex);
  }
 }
}

int ConnectedComponentLabeling(unsigned char *bitmap, int width, int height, int *labelmap){
 int cx, cy, index, popIndex, labelIndex = 0;
 Queue *queue = NULL;
 queue = (Queue*)malloc(sizeof(Queue));
 queue->first = NULL;
  queue->last = NULL;
 memset(labelmap, 0, width * height);
 for(cy = 1; cy < height - 1; cy++){
  for(cx = 1; cx < width - 1; cx++){
   index = cy * width + cx;
   if(bitmap[index] == 255 && labelmap[index] == 0){
    labelIndex++;
    SearchNeighbor(bitmap, width, height, labelmap, labelIndex, index, queue);

    popIndex = PopQueue(queue);
    while(popIndex > -1){
    SearchNeighbor(bitmap, width, height, labelmap, labelIndex, popIndex, queue);
     popIndex = PopQueue(queue);
    }
   }
  }
 }
 free(queue);
 return labelIndex;
}