The selection in worst case uses insertion sort to sort in step 2. but you would think insertion sort worst case running time is $O(n^2)$.but we are only sorting groups of 5 elements we know insertion sort is linear time for smaller values of n/. remember it beats megesort for smaller values of n. hence the step is linear time. Also dont use selection in worst case linear time because in practice it has large constants and it gets reduced by 19/20 n. it takes a while to be really small. use random selection in practice.
Saturday, March 2, 2013
selection in worst case linear time
The selection in worst case uses insertion sort to sort in step 2. but you would think insertion sort worst case running time is $O(n^2)$.but we are only sorting groups of 5 elements we know insertion sort is linear time for smaller values of n/. remember it beats megesort for smaller values of n. hence the step is linear time. Also dont use selection in worst case linear time because in practice it has large constants and it gets reduced by 19/20 n. it takes a while to be really small. use random selection in practice.
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