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| 1 | +class Solution(object): |
| 2 | + mod = 10**9 + 7 |
| 3 | + |
| 4 | + def multiplyMatrices(self, A, B): |
| 5 | + rowsA, colsA, colsB = len(A), len(A[0]), len(B[0]) |
| 6 | + result = [[0]*colsB for _ in range(rowsA)] |
| 7 | + for i in range(rowsA): |
| 8 | + for j in range(colsB): |
| 9 | + tmp = 0 |
| 10 | + for k in range(colsA): |
| 11 | + tmp += A[i][k] * B[k][j] |
| 12 | + result[i][j] = tmp % self.mod |
| 13 | + return result |
| 14 | + |
| 15 | + def powerMatrix(self, matrix, exponent): |
| 16 | + n = len(matrix) |
| 17 | + result = [[1 if i==j else 0 for j in range(n)] for i in range(n)] |
| 18 | + while exponent > 0: |
| 19 | + if exponent & 1: |
| 20 | + result = self.multiplyMatrices(result, matrix) |
| 21 | + matrix = self.multiplyMatrices(matrix, matrix) |
| 22 | + exponent >>= 1 |
| 23 | + return result |
| 24 | + |
| 25 | + def lengthAfterTransformations(self, s, t, nums): |
| 26 | + transform = [[0]*26 for _ in range(26)] |
| 27 | + for i in range(26): |
| 28 | + for shift in range(nums[i]): |
| 29 | + transform[i][(i + 1 + shift) % 26] += 1 |
| 30 | + transform = self.powerMatrix(transform, t) |
| 31 | + freq = [[0]*26] |
| 32 | + for ch in s: |
| 33 | + freq[0][ord(ch) - ord('a')] += 1 |
| 34 | + freq = self.multiplyMatrices(freq, transform) |
| 35 | + return sum(freq[0]) % self.mod |
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