Finding The Maximum On PRAM

Finding the maximum of n values in V is best done with max<< V, but it can be computed using Valiant’s algorithm



• In round i use all P (= n) processors to compare for all pairs of 2¦n numbers, finding the Ri max
  -- Round i
  x[j] := 1 -- initialize
  if V[j] <= V[k] then x[j]:=0 -- each k < j
  if x[j] = 1 then Ri := V[j] -- find winner
• Repeat same process on the maxes found
• The algorithm finds the global max in time O(loglog n)

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