Program: 101055
Project: 101055
Buggy source:
@Override public Iterable<String> predictiveSearch(String prefix){
  List<String> ret=new ArrayList<String>();
  char[] chars=prefix.toCharArray();
  int charsIndex=0;
  int nodeId=1;
  int start=0;
  int rootNodeId=-1;
  String pfx=null;
  while (true) {
    start=bv.select0(nodeId) + 1;
    int end=bv.next0(start);
    int baseNodeId=bv.rank1(start) - start;
    while (start != end) {
      int i=(start + end) / 2;
      int index=baseNodeId + i;
      int d=chars[charsIndex] - labels[index];
      int prevCharsIndex=charsIndex;
      if (d < 0) {
        end=i;
      }
 else       if (d > 0) {
        if (start == i)         return ret;
 else         start=i;
      }
 else {
        charsIndex++;
        if (charsIndex == chars.length) {
          rootNodeId=baseNodeId + i;
          pfx=new String(chars,0,prevCharsIndex);
          break;
        }
        int ti=tail[index];
        if (ti != -1) {
          TailCharIterator tci=new TailCharIterator(tails,ti);
          while (tci.hasNext()) {
            if (charsIndex == chars.length) {
              rootNodeId=baseNodeId + i;
              pfx=new String(chars,0,prevCharsIndex);
              break;
            }
            if (tci.next() != chars[charsIndex])             return ret;
            charsIndex++;
          }
        }
        nodeId=baseNodeId + i;
        break;
      }
    }
    if (pfx != null)     break;
    if (start == end)     return ret;
  }
  if (pfx == null)   return ret;
  Deque<Pair<Integer,String>> queue=new LinkedList<Pair<Integer,String>>();
  queue.offerLast(Pair.create(rootNodeId,pfx));
  while (queue.size() > 0) {
    Pair<Integer,String> element=queue.pollFirst();
    int nid=element.getFirst();
    StringBuilder b=new StringBuilder(element.getSecond());
    b.append(labels[nid]);
    int ti=tail[nid];
    if (ti != -1) {
      TailCharIterator it=new TailCharIterator(tails,tail[nid]);
      while (it.hasNext()) {
        b.append(it.next());
      }
    }
    String letter=b.toString();
    if (term.get(nid))     ret.add(letter);
    int s=bv.select0(nid) + 1;
    int e=bv.next0(s);
    int lastNodeId=bv.rank1(s) + e - s - 1;
    for (int i=(e - 1); i >= s; i--) {
      queue.offerFirst(Pair.create(lastNodeId--,letter));
    }
  }
  return ret;
}

Fixed version (ground truth):
@Override public Iterable<String> predictiveSearch(String query){
  List<String> ret=new ArrayList<String>();
  char[] chars=query.toCharArray();
  int charsLen=chars.length;
  int nodeId=0;
  TailCharIterator tci=new TailCharIterator(tails,-1);
  String pfx=null;
  for (int charsIndex=0; charsIndex < charsLen; charsIndex++) {
    int child=getChildNode(nodeId,chars[charsIndex]);
    if (child == -1)     return ret;
    int ti=tail[child];
    if (ti != -1) {
      tci.setIndex(ti);
      int charsIndexBack=charsIndex;
      while (tci.hasNext()) {
        charsIndex++;
        if (charsIndex >= charsLen) {
          pfx=new String(chars,0,charsIndexBack);
          break;
        }
        if (chars[charsIndex] != tci.next())         return ret;
      }
    }
    nodeId=child;
  }
  if (pfx == null)   pfx=query;
  Deque<Pair<Integer,String>> queue=new LinkedList<Pair<Integer,String>>();
  queue.offerLast(Pair.create(nodeId,pfx));
  while (queue.size() > 0) {
    Pair<Integer,String> element=queue.pollFirst();
    int nid=element.getFirst();
    StringBuilder b=new StringBuilder(element.getSecond());
    b.append(labels[nid]);
    int ti=tail[nid];
    if (ti != -1) {
      tci.setIndex(ti);
      while (tci.hasNext())       b.append(tci.next());
    }
    String letter=b.toString();
    if (term.get(nid))     ret.add(letter);
    int s=bv.select0(nid) + 1;
    int e=bv.next0(s);
    int lastNodeId=bv.rank1(s) + e - s - 1;
    for (int i=(e - 1); i >= s; i--) {
      queue.offerFirst(Pair.create(lastNodeId--,letter));
    }
  }
  return ret;
}