# Time: O(n) # Space: O(1) # Given an array of integers A and let n to be its length. # # Assume Bk to be an array obtained by rotating the array A # k positions clock-wise, we define a "rotation function" F on A as follow: # # F(k) = 0 * Bk[0] + 1 * Bk[1] + ... + (n-1) * Bk[n-1]. # # Calculate the maximum value of F(0), F(1), ..., F(n-1). # # Note: # n is guaranteed to be less than 105. # # Example: # # A = [4, 3, 2, 6] # # F(0) = (0 * 4) + (1 * 3) + (2 * 2) + (3 * 6) = 0 + 3 + 4 + 18 = 25 # F(1) = (0 * 6) + (1 * 4) + (2 * 3) + (3 * 2) = 0 + 4 + 6 + 6 = 16 # F(2) = (0 * 2) + (1 * 6) + (2 * 4) + (3 * 3) = 0 + 6 + 8 + 9 = 23 # F(3) = (0 * 3) + (1 * 2) + (2 * 6) + (3 * 4) = 0 + 2 + 12 + 12 = 26 # # So the maximum value of F(0), F(1), F(2), F(3) is F(3) = 26. class Solution(object): def maxRotateFunction(self, A): """ :type A: List[int] :rtype: int """ s = sum(A) fi = 0 for i in xrange(len(A)): fi += i * A[i] result = fi for i in xrange(1, len(A)+1): fi += s - len(A) * A[-i] result = max(result, fi) return result