title: PHP array collect
body: <p>I have alphabet array 24 character: "A  B   C   D   E   F   G   H   I   J   K   L   M   N   O   P   Q   R   S   T   U   V   W   X"</p>
  
  <p>I want collect all case with: 3 unique characters.</p>
  
  <p>First case: ABC, DEF, GHI, JKL, MNO, PQR, STU, VWX</p>