-
Notifications
You must be signed in to change notification settings - Fork 0
/
prob23_inversions.py
150 lines (135 loc) · 3.93 KB
/
prob23_inversions.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
##def inversionCount(array):
## inv = 0
## for i in range(0,len(array)-1):
## #print "i",i
## j = i+1
## while j < len(array):
## if array[i] > array[j]:
## inv += 1
## j += 1
## return inv
##def mergeSort(array,inv):
## """
## Takes a list and sorts it in place with merge sort
## """
## n = len(array)
## if n > 1:
## mid = n//2
## left = array[:mid]
## right = array[mid:]
## mergeSort(left,inv)
## mergeSort(right,inv)
## i=0
## j=0
## k=0
## while i < len(left) and j < len(right):
## print "left",left[i],"right",right[j]
## print "inv",inv
## if left[i] < right[j]:
## array[k]=left[i]
## i += 1
## else:
## print "inv!"
## array[k]=right[j]
## j += 1
## inv += 1
## k += 1
## while i < len(left):
## array[k]=left[i]
## i += 1
## k += 1
## while j < len(right):
## array[k]=right[j]
## j += 1
## k += 1
## return array,inv
def mergeCount(listA,listB): ## A and B are sorted lists
i = 0
j = 0
inv = 0
OutList = []
while i < len(listA) and j < len(listB): ## not at end of a list
#print "listA","listB"
#print listA[i],listB[j]
nextNum = min(listA[i],listB[j])
OutList.append(nextNum)
if listB[j] == nextNum:
j = j + 1
inv += len(listA) - i ##inc by num left in A
else:
i = i + 1
while i < len(listA):
OutList.append(listA[i])
i = i + 1
while j < len(listB):
OutList.append(listB[j])
j = j + 1
#print "inv","outlist"
#print inv,OutList
return inv,OutList
#return inv
def sortCount(listL):
if len(listL) == 1:
#print "single item"
#print 0,listL
return 0,listL
else:
n = len(listL)
mid = n//2
listA = listL[:mid]
listB = listL[mid:]
#print "split lists"
#print listA,listB
invA,sortedA = sortCount(listA)
invB,sortedB = sortCount(listB)
crossInv, sortedL = mergeCount(sortedA, sortedB)
#print "after merge"
#print (invA + invB + crossInv),sortedL
return (invA + invB + crossInv),sortedL
##def inversionCount2(array):
## copy = array[:]
## sort = array[:]
## sort = mergeSort(sort)
## inv = 0
## #print copy
## #print sort
## while len(copy) > 1:
## find = copy[0]
## loc = sort.index(find)
## #print "find",find
## #print "loc",loc
## inv += loc
## #print "inv",inv
## copy.remove(find)
## sort.remove(find)
## #print copy
## #print sort
## return inv
def main():
infile = open("C:/Users/Kaiya/Desktop/rosalind_inv.txt","rU")
#infile = open("C:/Users/Kaiya/Desktop/scratch_rosalind.txt","rU")
n = infile.readline()
aList = infile.readline()
infile.close()
n = n.strip()
n = int(n)
aList = aList.strip()
aList = aList.split(" ")
aList = [int(i) for i in aList]
print "file read"
#print "aList 0:5",
#print aList[0:5]
ans = sortCount(aList)
print "inversions: ",
print ans[0]
outfile = open("C:/Users/Kaiya/Desktop/rosalind_inv_ans.txt","w")
#outfile = open("C:/Users/Kaiya/Desktop/scratch_rosalind_2.txt","w")
print >>outfile, ans[0]
outfile.close()
print "done"
if __name__ == "__main__":
#import timeit
#import random
#array = [random.random() for i in range(3000)]
#print(timeit.timeit("inversionCount(array)", setup="from __main__ import inversionCount,array", number=10))
main()