Create 0689_maximum-sum-of-3-non-overlapping-subarrays.py

LeetCode/0689_maximum-sum-of-3-non-overlapping-subarrays.py

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+class Solution(object):
+ def maxSumOfThreeSubarrays(self, nums, k):
+ """
+ :type nums: List[int]
+ :type k: int
+ :rtype: List[int]
+ """
+ n = len(nums)
+ accu = [0]
+ for num in nums:
+ accu.append(accu[-1]+num)
+
+ left_pos = [0] * n
+ total = accu[k]-accu[0]
+ for i in xrange(k, n):
+ if accu[i+1]-accu[i+1-k] > total:
+ left_pos[i] = i+1-k
+ total = accu[i+1]-accu[i+1-k]
+ else:
+ left_pos[i] = left_pos[i-1]
+
+ right_pos = [n-k] * n
+ total = accu[n]-accu[n-k]
+ for i in reversed(xrange(n-k)):
+ if accu[i+k]-accu[i] > total:
+ right_pos[i] = i
+ total = accu[i+k]-accu[i]
+ else:
+ right_pos[i] = right_pos[i+1]
+
+ result, max_sum = [], 0
+ for i in xrange(k, n-2*k+1):
+ left, right = left_pos[i-1], right_pos[i+k]
+ total = (accu[i+k]-accu[i]) + \
+ (accu[left+k]-accu[left]) + \
+ (accu[right+k]-accu[right])
+ if total > max_sum:
+ max_sum = total
+ result = [left, i, right]
+ return result