leetcode1020

 1 class Solution(object):
 2     def canThreePartsEqualSum(self, A: ‘List[int]‘) -> bool:
 3         n = len(A)
 4         sums = sum(A)
 5         if sums % 3 != 0:
 6             return False
 7         target = sums // 3
 8         
 9         leftpart = 0
10         leftboundary = n -1
11         for i in range(n-2):
12             leftpart += A[i]
13             if leftpart == target:
14                 leftboundary = i
15                 break
16                 
17         rightpart = 0
18         rightboundary = 0
19         for j in range(n-1,1,-1):
20             rightpart += A[j]
21             if rightpart == target:
22                 rightboundary = j
23                 break
24         
25         if leftboundary < rightboundary:
26             return True
27         return False