The characteristics and implementation of merging and sorting [C language]

The characteristics and implementation of merging and sorting [C language]

1. Algorithm characteristics

Merge sort is an efficient and stable sorting method, which is second only to fast sorting, but is more memory-intensive.

The time complexity is the best, the worst, the average condition is O (nlog (2) n), the spatial complexity is O (n).

2. Algorithm Ideas

Divide and conquer the idea of the problem decomposition, refinement, one by one, that is, by recursion to decompose the sequence of disorder, until decomposed into a sequential sequence (when the sequence length of 1 must be ordered). Then, the ordered sequence of decomposition is merged into a new ordered sequence, and finally merged into an ordered sequence.

3. Implementation code

1#include <stdio.h>2#include <stdlib.h>3 4 //Merge sort: arr [left,mid] interval ascending [mid+1,rigth] ascending merges the data of this array in ascending order5 voidMergeintArr[],intLeftintMidintrigth)6 {7     intLen = mid-left+1;8     int* p =malloc(sizeof(int)*len);9     //moving data from the [left,mid-1] interval to the memory that P points toTen     //memcpy (prr,arr+left,l1*sizeof (int)); One      for(intI=0; i<len; i++) A     { -P[i] = arr[left+i]; -     } the     //merge p[0,len-1] arr[mid,rigth] Two pieces of data into the Arr[left,rigth] array -     inti =0; -     intj = mid+1; -     intK = left;//start from left +      while(I<len && j<=rigth) -     { +         if(P[i] <Arr[j]) A         { atarr[k++] = p[i++];  -         } -         Else -         { -arr[k++] = arr[j++];  -         } in     } -      while(I <len) to     { +arr[k++] = p[i++];  -     } the } *  $ //Bunkhouse The arr left-rigth interval orderlyPanax Notoginseng void_merge_sort (intArr[],intLeftintrigth) - { the     if(left >= rigth)//There 's only one data that would have been ordered . +     { A         return; the     } +     intMid = (left+rigth)/2; -     //Left mid mid+1 rigth $     if(Mid >Left ) $     { -_merge_sort (Arr,left,mid);//make array [left,mid] orderly -     } the     if(Rigth > mid+1) -     {Wuyi_merge_sort (arr,mid+1, rigth);//make array [mid+1,rigth] orderly the     } -Merge (Arr,left,mid,rigth);//Merging Wu } -  About voidMerge_sort (intArr[],intlen) $ { -_merge_sort (arr,0, len-1); - } -  A voidTravelintArr[],intlen) + { the      for(intI=0; i<len; i++) -     { $printf"%d", Arr[i]);  the     }     theprintf"\ n"); the } the  - intMain () in { the     intArr[] = { -, the,9,233, +, -, -,9,4, the}; the     intLen =sizeof(arr)/sizeof(arr[0]); About  the Travel (Arr,len); the Merge_sort (Arr,len); the Travel (Arr,len); +  -     return 0; the}

4. Test results

The characteristics and implementation of merging and sorting [C language]