Order Statistics Algorithm Quicksort(A, first, last) if first < - - PowerPoint PPT Presentation

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Dec 20, 2022 22 likes •56 views

Order Statistics Algorithm Quicksort(A, first, last) if first < last then // // Partition reorders A[first . . . last] so // All elements of A[first . . . mid - 1] are A[mid] // All elements of A[mid + 1 . . . last] are > A[mid] //

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Order Statistics

Algorithm Quicksort(A, first, last) if first < last then // // Partition reorders A[first . . . last] so // All elements of A[first . . . mid - 1] are ≤ A[mid] // All elements of A[mid+1 . . . last] are > A[mid] // The original value of A[last] ends up as A[mid] mid ← Partition(A, first, last) Quicksort(A, first, mid−1) Quicksort(A, mid+1, last)

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Order Statistics

Algorithm Select1(A, first, last, i) if first = last then return A[first] mid ← Partition(A, first, last) leftsize ← mid − first if i = leftsize+1 then return A[mid] if i ≤ leftsize then return Select1(A, first, mid−1, i) return Select1(A, mid+1, last, i−(leftsize+1))

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Order Statistics

Algorithm RandomizedQuickSelect(A, first, last, i) if first = last then return A[first] mid ← RandomizedPartition(A, first, last) leftsize ← mid − first if i = leftsize+1 then return A[mid] if i ≤ leftsize then return RandomizedQuickSelect(A, first, mid−1, i) return RandomizedQuickSelect(A, mid+1, last, i−(leftsize+1))