减治法——搜索第k小元素(Decrease and Conquer by a Factor - Finding the kth smallest element)

减治法——搜索第k小元素(Decrease and Conquer by a Factor - Finding the kth smallest element)

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问题(Problem)
Find the kth smallest element in an unsorted array.

分割(Partitioning)
Partitioning an array around some pivot element p means reorganising the array so that all elements to the left of p are no greater than p, while those to the right are now smaller.

Lomuto Partitioning

function LomutoPartition(A[lo..hi])
    p ⟵ A[lo]
    s ⟵ lo
    for i ⟵ lo+