-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathMaxSubarray.py
More file actions
46 lines (37 loc) · 1.25 KB
/
MaxSubarray.py
File metadata and controls
46 lines (37 loc) · 1.25 KB
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
# HI RUNT!
inf = 9999999999999999999999999
def findMaxCrossingSubarray(a, low, mid, high):
leftsum = -inf
sum = 0
maxleft = None
for i in range(mid, low, -1):
sum = sum + a[i]
if (leftsum is None) or (sum>leftsum):
leftsum = sum
maxleft = i
rightsum = -inf
sum = 0
maxright = None
for i in range(mid+1, high, +1):
sum = sum + a[i]
if (rightsum is None) or (sum>rightsum):
rightsum = sum
maxright = i
return (maxleft, maxright, leftsum+rightsum)
def maxSubArray(a, low, high):
if (low==high):
return (low, high, a[low])
else:
mid = int((high+low)/2)
print (low, mid, high)
(leftlow, lefthigh, leftsum) = maxSubArray(a, low, mid)
(midlow, midhigh, midsum) = findMaxCrossingSubarray(a, low, mid, high)
(rightlow, righthigh, rightsum) = maxSubArray(a, mid+1, high)
if (leftsum > midsum) and (leftsum > rightsum):
return (leftlow, lefthigh, leftsum)
elif (rightsum > midsum) and (rightsum > leftsum):
return (rightlow, righthigh, rightsum)
else:
return (midlow, midhigh, midsum)
def msa(a):
return maxSubArray(a, 0, len(a)-1)