Quick Sorting Algorithm

Quick sorting is based onSub-governance mode.

I. Basic Ideas:

1. Find a benchmark number;

2. re-arrange the sequence, put the smaller value than the benchmark number in front, and put the larger value than the benchmark number in the back. After the split, the benchmark number is the intermediate number, which is also a split operation;

3. recursively reorder the two sequences separated by the reference number.

Quick sorting isRecursive thinkingClassic application.

This algorithm was proposed by Mr. Tony Karl in 1962.

Ii. decomposition method:

Array a [p... R] is divided into two child arrays that may be null A [p... q-1] <= A [Q] <= A [q + 1 .. R].

Iii. solution:
Perform quick sorting by recursive calling.

Iv. Merge:

Because the two sub-arrays are sorted in place, they do not need to be merged.

5. pseudocode:

Because there are many versions of the Sorting Algorithm, select the version used in introduction to algorithms, that is, use the last element of the array as the principal component for sorting.

QUICKSORT(A,p,r) If(p<r)   Then q←PARTION(A,p,r)              QUICKSORT(A,p,q-1)              QUICKSORT(A,q+1,r) PARTION(A,p,r)x←A[r]i←p-1forj←p to r-1   do if A[j]<=x      then i←i+1         exchange A[i]A[j]exchange A[i+1]A[r]return i+1

6. Source Code implementation:

# Include <stdio. h> # include <stdlib. h> # define Max 8 void Exchange (int * X, int * Y) // the pointer must be used here, otherwise, the parameter value {int temp; temp = * X; * x = * Y; * Y = temp;} of the called function cannot be changed because of function copy ;} int partion (int v [], int P, int R) {int x = V [R]; int I = p-1; Int J; For (j = P; j <= R-1; j ++) {If (V [J] <X) {I ++; Exchange (& V [I], & V [J]) ;}} Exchange (& V [I + 1], & V [R]); return I + 1;} void quicksort (INT V [], int P, int R) {int q = 0; If (P <r) {q = partion (v, P, R); quicksort (V, p, q-1 ); quicksort (v, q + 1, R) ;}} int main () {int V [Max]; for (INT I = 0; I <Max; I ++) scanf ("% d", & V [I]); quicksort (v, 0, MAX-1); For (Int J = 0; j <Max; j ++) printf ("% d \ t", V [J]); System ("pause"); Return 0 ;}

VII. Running result:

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8. algorithm Demonstration:

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Quick Sorting Algorithm