算法导论 第一章and第二章(python)

def INSERTION_SORT(A):
    for j in range(1,len(A)): # ython[,) #算法导论从1开始 python list从0开始
        #print(A[j]) #test
        key = A[j]
        i = j - 1
        while i >=0 and A[i] > key:
            A[i + 1] = A[i]
            i -= 1
        A[i + 1] = key

if __name__ == ‘__main__‘:
    A = [5,2,6,1,3]
    INSERTION_SORT(A) # 和java 传值相识 c指针？：**p
    print(A)

  
import decimal
def MERGE(A,p,q,r): #归并
    n1 = q - p +1
    n2 = r - q
    L = []
    R = []
    for i in range(n1):
        L.append(A[p + i]) # 0开始
    for j in range(n2):
        R.append(A[q + j+1]) #A[q+1 ,r]
    L.append(decimal.MAX_EMAX ) #10机制模块64位999999999999999999 
    R.append(decimal.MAX_EMAX)
    i = 0
    j = 0
    for k in range(p,r+1): #A[p,r]
        if L[i] <= R[j]:
            A[k] = L[i]
            i += 1
        else:
            A[k] = R[j]
            j += 1
 
def MERGE_SORT(A,p,r): #A[p,r]
    if p < r:
        q = (p + r)//2 
        MERGE_SORT(A,p,q)
        MERGE_SORT(A,q+1,r)
        MERGE(A,p,q,r)
 
if __name__ == ‘__main__‘:
    A = [5,2,4,7,1,3,2,6]
    print(A)
    MERGE_SORT(A,0,len(A)-1) 
    print(A)
 
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结果：
============== RESTART: F:\python\algorithms\2_3_merge_sort.py ==============
[5, 2, 4, 7, 1, 3, 2, 6]
[1, 2, 2, 3, 4, 5, 6, 7]
环境：win7 python3.5.1
注意： A区间的选取 python 的list从0开始 我选的是[ , ]
 
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