8. Bubble Sorting and quick sort (based on OPENCV)

First, preface

This paper mainly describes the basic process of bubble sorting and quick sorting, and gives the code implementation, and the pro-test is available.

Second, bubble method sort

The bubble method is mainly to compare the adjacent two values, the small forward bubble, large back precipitation, time complexity of O (N2). The main ideas are as follows:

divided into internal and external loops, each outer loop to determine the specific location of a large data, the following example:

As can be seen, in two times the outer loop can be sorted results, the subsequent 8 cycles are wasted, in order to avoid this situation, we can set a state parameter, used to indicate whether the inner loop is the exchange of data, so as to whether the outer loop exits the signal.

Three, quick sort

Fast sorting is one of the most effective sorting methods, the main idea is to sort the data separately, by selecting a cardinality, then dividing the data to be sorted into two parts, all large and small on one side. Then the recursive idea is used to sort the separate data.

Iv. implementation of the Code

Bubble sort (the position of the output sorted data in the original data):

1 voidSparsegraphic::bubblesort (ConstCv::mat Inmat, qvector<int> &index, Cv::mat &Outmat)2 {3     if(inmat.rows!=1)4         return;5     intCol =Inmat.cols;6index = qvector<int>(col);7      for(inti =0; i<col;i++)8     {9Index[i] =i;Ten     } One     if(Inmat.type ()! =cv_32f) A Inmat.convertto (inmat,cv_32f); -Outmat =Inmat.clone (); -  the     float*ptr = outmat.ptr<float> (0); -     floatTmpval; -     intTmpidx; -      for(inti =0; i<col;i++) +     { -          for(intj =0; J<col-i-1; j + +) +         { A             if(ptr[j]>ptr[j+1]) at             { -Tmpval =Ptr[j]; -ptr[j]=ptr[j+1]; -ptr[j+1]=Tmpval; -Tmpidx =Index[j]; -INDEX[J] = index[j+1]; inindex[j+1] =Tmpidx; -             } to         } +     } -}

Quick sort (outputs the position of the data in the source data after sorting):

1 voidSparsegraphic::quicksort (Cv::mat Inmat, qvector<int> &index,intLowintHigh )2 {3     if(inmat.rows!=1)4         return;5     float*ptr = inmat.ptr<float> (0);6     if(Low <High )7     {8         inti = Low,j =High ;9         floatX =Ptr[low];Ten          while(i<j) One         { A              while(I<j && Ptr[j] >=X) -j--; -             if(i<j) the             { -ptr[i++] =Ptr[j]; -                 intTMP =Index[j]; -INDEX[J] = index[i-1]; +index[i-1] =tmp; -             } +  A              while(I<j && Ptr[i] <X) ati++; -             if(i<j) -             { -ptr[j--] =Ptr[i]; -                 intTMP =Index[i]; -Index[i] = index[j+1]; inindex[j+1] =tmp; -             } to         } +Ptr[i] =X; -QuickSort (inmat,index,low,i-1); theQuickSort (inmat,index,i+1, high); *     } $}

8. Bubble Sorting and quick sort (based on OPENCV)