Algorithm: three simple sorting algorithms

sorting algorithms are more common: bubble sort, simple selection sort, direct insert sort, hill sort, heap sort, merge sort and fast sort algorithm, etc. Learn the first three simple algorithms today. Related concepts of sorting:

① the stability of the sort: two or more elements are equal, and the order is still the same, and the ordering is stable.

② internal ordering: The sorting process is done in memory; external sort: a sort procedure that requires external access.

③ ranking Algorithm performance factors: 1, time performance, comparison and movement, 2, auxiliary space; 3, algorithmic complexity

Example: Bubble sort, simple select sort and direct Insert sort

#include "stdio.h" #define MAXSIZE 6int data[maxsize] = {0,5,4,3,2,1};/** function: array element Exchange * Input: data, swap element subscript * Output: no */void swap (int Data[],int I,int j) {int temp = Data[i];d ata[i] = data[j];d ata[j] = temp;} /** function: Bubble sort * Input: Array * output: no * algorithm: Loop once, subscript location is the minimum value, constantly compare and move */void bubble1 (int data[]) {for (int i = 0; i < MAXSIZE-1; i++) for (i NT J = i+1; J < MAXSIZE; J + +) if (Data[j] < data[i]) swap (DATA,I,J);}  /** function: Improved bubble sort * Input: Array * output: no * algorithm: Improved algorithm in addition to focus on the current minimum value, you can also move other smaller values in front */void bubble2 (int data[]) {int flag = 1;  Flag bit for (int i = 0; i < MAXSIZE-1 && flag; i++) {flag = 0; Each loop flag bit is assigned 0for (int j = MAXSIZE-1; j > i; j--) if (Data[j] < data[j-1])//adjacent to two elements before the comparison, rather than the above algorithm focusing only on the minimum value.  {swap (DATA,J-1,J); flag = 1; When a move occurs, it is assigned to 1, otherwise the sort is completed without unnecessary comparisons. }}}/** function: Simple selection sort * Input: Array * output: no * algorithm: Compare the lowest value of the subscript, the last move, instead of each comparison after the move */void easy (int data[]) {int min = 0;for (int i = 0; i < MAX SIZE-1;  i++) {min = i; Suppose that the first subscript is the minimum value for (int j = i+1; J < MAXSIZE; J + +) {if (Data[j] < data[min])//When there is less data than the first subscript, record its subscript min = j;}  if (min! = i)Swap swap If the minimum value is not the first subscript (data,min,i);}} /** function: Direct Insert sort * Input: Array * output: no * algorithm: Insert data into the ordered table that has already been ordered, get the ordered table with record increment 1.  */void insertsort (int data[]) {for (int i = 2; i < MAXSIZE; i++)//First loop, sort data[1],data[2] two elements, data[0] is Sentinel action {if (Data[i] < data[i-1])//If DATA[2] is smaller than data[1], Sentinel Data[0] set to data[2]{data[0] = data[i];int j = i;while (Data[j-1] > Data[0])//When DATA[1] > Data[0], move it right to data[2] = data[1]{data[j] = data[j-1];j--;}  DATA[J] = data[0]; DATA[1] = data[0], to achieve the exchange of data[1] and data[2],//At this time data[1] and data[2] is ordered orderly table, the beginning of the second loop}}}void print (int *data) {for (int i = 0; i < MAXSIZE; i++) printf ("%d", Data[i]);p rintf ("\ n");} int main (int argc, char* argv[]) {print (data),//bubble1 (data),//bubble2 (data),//simple (data), Insertsort (data);p rint (data);}

Summary: The time complexity of the three simple sorting algorithms is O (n^2), which is a stable sort.

Algorithm: three simple sorting algorithms