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What are the differences between this three sort functions in Mo's algo?

First approach:

bool comp(stt q1, stt q2)
{
    int block_a = q1.l / sq, block_b = q2.l / sq;
    if(block_a == block_b)
        return q1.r < q2.r;
    return block_a < block_b;
}

Second approach:

bool comp(stt q1, stt q2)
{
  if (q1.l / sq != q2.l / sq) return q1.l< q2.l;
  return (q1.r < q2.r)^(q1.l/sq%2);
}

Third approach:

bool comp(stt q1, stt q2)
{
    if(q1.l/sq != q2.l/sq)
    {
        return q1.l < q2.l;
    }
    if((q1.l/sq) & 1)
    {
        return q1.r < q2.r;
    }
    return q1.r > q2.r;
}

Problem link

The first approach gives the TLE on test 9 Submission linkthe second approach gives the TLE on test 67 Submission linkbut the third approach gives AC Submission link. Thanks in advance. :)