Quadratic probing is like linear probing, but instead of checking the next slot sequentially, it jumps by increasing squares: h+1², h+2², h+3², etc. This helps avoid the "clustering" problem where many consecutive slots fill up.

  h(22) = 22 mod 7 = 1

  Collision at 1? Try:
    (1 + 1²) mod 7 = 2
    (1 + 2²) mod 7 = 5
    (1 + 3²) mod 7 = 3

  Jumps:  +1  +4  +9  +16 ...
  Avoids clustering!