插入合并排序对比实验--伪代码+完整代码

直接插入排序伪代码：

ALGORITHM InsertionSort( A[0..n-1] ) // 对给定序列进行直接插入排序

// 输入：大小为n的无序序列A

// 输出：按非递减排列的序列

A for i ← 1 to n-1 do   

         temp ← A[i]   

          j ← i-1

           while j ≥ 0 and A[j] > temp do

                   A[j+1] ← A[j]  

                   j ← j –1

           A[j+1] ←temp

合并排序的递归算法伪代码：

 算法 MergeSort(A[0..n-1] )    

// 输入：未排序序列A[0..n-1]    

// 输出：已排序序列A[0..n-1]    

if n > 1   

  copy A[0..n/2-1] to B[0..n/2-1]     

  copy A[n/2..n-1] to C[0..n/2-1]        

  MergeSort( B )        

  MergeSort( C )         

  Merge( B,C,A )      

其中，Merge(B,C,A)是将有序数组B、C合并为有序数组A的算法。

算法 Merge(B[0..p-1],C[0..q-1],A[0..p+q-1])    

i=0,j=0,k=0;    

while i

         if B[i]≤C[j]

            A[k]=B[i], i=i+1

        else

            A[k]=C[j], j=j+1

        k=k+1

      if i=p  

          copy C[i..q-1] to A[k..p+q-1]

     else  

          copy B[0..p-1] to A[0..p+q-1]     

 完整对比代码

import time

from functools import wraps

from timeit import default_timer as timer

import random

import matplotlib.pyplot as plt

def timefn(fn):

    """计算性能的修饰器"""

    @wraps(fn)

    def measure_time(*args, **kwargs):

        t1 = time.time()

        result = fn(*args, **kwargs)

        t2 = time.time()

        return result

    return measure_time

@timefn

def disort(a):                                # 直接插入排序

    l=len(a)

    for i in range(l):

        temp = a[i]

        j = i-1

        while j >= 0 and a[j] > temp:

            a[j+1] = a[j]

            j = j-1

        a[j+1] = temp

    return a

def mergesort(a):                              # 合并排序功能函数

    l = len(a)

    b = []

    c = []

    b = a[0:l//2+l%2:1]

    c = a[l//2+l%2::1]

    b.sort()

    print(b)

    c.sort()

    print(c)

    a=[]

    i=0

    j=0

    while i

        if b[i]>c[j]:

            a.append(c[j])

            j+=1

        else:

            a.append(b[i])

            i+=1

    if i==l//2+l%2:                          # 循环关键部分

        a=a+c[j::1]

    if j==l//2+l%2:                          # 若没有此处的if程序健壮性不强

        a=a+b[i::1]

    return a

listtime1=[]

listtime2=[]

for m in range(1,22102,2000):                 # 随机生成测试list

    b=[random.randint(0,1000)for i in range(m)]

    tic = timer()

    mergesort(b)

    tic1= timer()

    disort(b)

    tic2=timer()

    listtime1.append(tic1 - tic)

    listtime2.append(tic2 - tic1)

y1=listtime1

y2=listtime2

print(y1)

print(y2)

def plot_double_lines(n, x, y1, y2, pic_name):         # 绘制图标

    # initialize plot parameters

    print('picture name: %s, len of data: %d' % (pic_name, n))

    plt.rcParams['figure.figsize'] = (10 * 16 / 9, 10)

    plt.subplots_adjust(left=0.06, right=0.94, top=0.92, bottom=0.08)

    # plot curve 1

    plt.plot(x, y1, label='mergesort')

    # plot curve 2

    plt.plot(x, y2, label='disort')

    # show the legend

    plt.legend()

    # show the picture

    plt.show()

if __name__ == '__main__':

    xs = range(1,22102,2000)

    y1s = listtime1

    y2s = listtime2

plot_double_lines(len(xs), xs, y1s, y2s, 'Two Curves')

对比关系图：纵坐标单位’s’