Quick sort
Quicksort (sometimes called partition-exchange sort) is an O(N log N) efficient sorting algorithm, serving as a systematic method for placing the elements of an array in order. Developed by British computer scientist Tony Hoare in 1959[1] and published in 1961,[2] it is still a commonly used algorithm for sorting. When implemented well, it can be about two or three times faster than its main competitors, merge sort and heapsort.[3][contradictory] Quicksort is a comparison sort, meaning that it can sort items of any type for which a "less-than" relation (formally, a total order) is defined. In efficient implementations it is not a stable sort, meaning that the relative order of equal sort items is not preserved. Quicksort can operate in-place on an array, requiring small additional amounts of memory to perform the sorting. It is very similar to selection sort, except that it does not always choose worst-case partition.
Clicking on this step you can see the Create code learningstep of the algorithm.
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void quick_sort(int a[], int i, int j){
if ( i < j ){
int k = pre_sort(a,i,j);
quick_sort( a, , );
quick_sort( a, , );
}
}
int pre_sort (int a[], int i, int j){
int temp, pivot = a[i];
while ( i < j ){
if ( a[i] > a[j] ) {temp = a[i]; a[i] = a[j]; a[j] = temp;}
else if ( a[i] == pivot ) {++i;}
else {--j;}
}
return i;
}
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1. Identify the cycle structure!
1. Listening
Listen carefully, and try to understand
the cycle structure that may exist in this algorithm!
2. Choosing structure
Now choose the cycle structure:
Congratulations! You've chosen the right structure!
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