C++ bubber sort

bubber sort:， 也就是常说的冒泡法排序。 是所有排序算法中比较简单地一个了。

bubber sort 的伪代码如下：

procedure bubbleSort( A:list of sortable items)

n = length(A)

repeat

swapped = false

for i = 1to n-1 inclusivedo

/* if this pair is out of order */

if A[i-1]> A[i]then

/* swap them and remember something changed */

swap( A[i-1], A[i])

swapped = true

end
if

end for

until not swapped

end
procedure



举个例子， the array of numbers "5 1 4 2 8"，使用bubber sort 从小到大的对这个数组排序。 则有如下：



Now, the array is already sorted, but our algorithm does not know if it is completed.

The algorithm needs one whole pass without any swap to know it is sorted.（注意啊 ， 算法并没有结束）





bubber sort的算法分析：

冒泡排序的最坏的时间复杂度是O(n^2)。



程序如下：

//Bubber sort for array based list

#include <iostream>
#include <ctime>
#include <cstdlib> // 产生随机数
#include <iomanip>

using namespace std;

template <class elemType>
void print(elemType list[], int length);

// do swap

template <class elemType>
void swap(elemType[], int, int);

//bubber sort 总程序
template <class elemType>
void bubberSort(elemType[], int);

int main() {
   int intList[100];
   int num;
   for (int i = 0; i < 100; i++){
      num = (rand() + time(0)) %1000;
      intList[i] = num;
   }
   cout << "intList before sorting: " << endl;
   print(intList, 100);
   cout << endl << endl;
   bubberSort(intList, 100);
   cout << "intList after bubber sort: " << endl;

   print(intList, 100);
   cout << endl;

   system("Pause");
   return 0;

}

template <class elemType>
void print(elemType list[], int length) {
   int count = 0;
   for(int i = 0; i < length; i++) {
      cout << setw(5) << list[i];
      count++;
      if(count % 10 == 0)
         cout << endl;
   }
}

template <class elemType>
void swap(elemType list[], int first, int second) {
   elemType temp;
   temp = list[first];
   list[first] = list[second];
   list[second] = temp;
}

template <class elemType>
void bubberSort(elemType list[], int length) {
   bool swaped = true;

   while(swaped) {
      swaped = false;
      for (int i = 1 ; i < length; i++) {

         if(list[i-1] > list[i]) {
            swap(list, i - 1, i);
            swaped = true;
         }
      }
   }

}

运行结果为：





上述的程序是我根据伪代码编写的。

视频tutorial的代码如下：

//Bubber sort for array based list

#include <iostream>
#include <ctime>
#include <cstdlib> // 产生随机数
#include <iomanip>

using namespace std;

template <class elemType>
void print(elemType list[], int length);

//bubber sort
template <class elemType>
void bubberSort(elemType[], int);

int main() {
   int intList[100];
   int num;
   for (int i = 0; i < 100; i++){
      num = (rand() + time(0)) %1000;
      intList[i] = num;
   }
   cout << "intList before sorting: " << endl;
   print(intList, 100);
   cout << endl << endl;
   bubberSort(intList, 100);
   cout << "intList after bubber sort: " << endl;

   print(intList, 100);
   cout << endl;

   system("Pause");
   return 0;

}

template <class elemType>
void print(elemType list[], int length) {
   int count = 0;
   for(int i = 0; i < length; i++) {
      cout << setw(5) << list[i];
      count++;
      if(count % 10 == 0)
         cout << endl;
   }
}

template <class elemType>
void bubberSort(elemType list[], int length) {
  for (int i = 1; i < length; i++) { // i is 第几次的 iteration
     for (int index = 0; index < length - 1; index++) {
        if(list[index] > list[index + 1]) {
           elemType temp = list[index];
           list[index] = list[index + 1];
           list[index + 1] = temp;
        }
     }
  }
}

运行结果如下：



不难看出， 最坏的情况的时间复杂度是： O（n^2）