Does quicksort use more comparisons than mergesort? If so, then why is it a faster sorting algorithm?

http://en.wikipedia.org/wiki/Merge_sort In the worst case, merge sort does about 39% fewer comparisons than quicksort does in the average case; merge sort always makes fewer comparisons than quicksort.. merge sort is stable than quick sort. -> why it is faster? you keep dividing the numbers into sub divisions until you reach 1 element in each sub divisions. if you check the diagram in wiki (http://upload.wikimedia.org/wikipedia/commons/thumb/e/e6/Merge_sort_algorithm_diagram.svg/300px-Merge_sort_algorithm_diagram.svg.png), you only sort within each divisions and then merge them. in regular sorting you would begin from the first number and compare it with every other elements.. example: 3 2 7 1 REGULAR SORT(how humans would do!!) ->you start from 3, compare it with 2, swap them (2 3 7 1). -> compare 3 with 7 and just keep them as it is (2 3 7 1) -> compare 3 with 1 and swap them (2 1 7 3) -> this process goes on and on MERGE SORT: divide them to divisions. -> [3 2] [7 1] -> [[ 3] [2]] [[7] [1]] -> now start from left in each divisions, swap them if needed with in each divisions and merge them. [2 3] [1 7] -> again start from left. compare 2 and 1 (first elements with each divisions) [1 2 ], sort them and move them to bigger box. next compare 3 and 7. move them to bigger fox [1 2 3 7]. [1 2 3 7] it can be more clear if you look the animation. you ll realize merge sort is faster than regular sorting. -> if you analyze quick sort, it looks wacky and merge sort looks more stable!

Both algorithm complexity of order same O(NlogN) where N is number of elements. Both recursive also. Both involves movements of elements. quicksorting has both best and worst case behaviors. For large value of N, quicksorting does use less number of computations.

Both algorithm complexity of order same O(NlogN) where N is number of elements. Both recursive also. Both involves movements of elements. quicksorting has both best and worst case behaviors. For large value of N, quicksorting does use less number of computations.