it is slow, costs nearly 2 seconds, but I think it is easy to understand

```
class Solution(object):
def splitArray(self, nums):
"""
:type nums: List[int]
:rtype: bool
"""
n = len(nums)
sums = [0] * (n + 1)
for i in xrange(n):
sums[i + 1] = sums[i] + nums[i]
for j in xrange(3, n - 3):
s = set()
for i in xrange(1, j - 1):
if sums[i] == (sums[j] - sums[i+1]):
s.add(sums[i])
for k in xrange(j + 2, n - 1):
sjk = sums[k] - sums[j+1]
skn = sums[n] - sums[k+1]
if sjk == skn and sjk in s:
return True
return False
```