May 14

Author: siddydutta

2025-05-May-LeetCoding-Challenge/README.md

@@ -17,7 +17,7 @@
 | May 11 | [1550. Three Consecutive Odds](https://leetcode.com/problems/three-consecutive-odds/) | Easy | Solved |
 | May 12 | [2094. Finding 3-Digit Even Numbers](https://leetcode.com/problems/finding-3-digit-even-numbers/) | Easy | Solved |
 | May 13 | [3335. Total Characters in String After Transformations I](https://leetcode.com/problems/total-characters-in-string-after-transformations-i/) | Medium | Solved |
-| May 14 | []() |  |  |
+| May 14 | [3337. Total Characters in String After Transformations II](https://leetcode.com/problems/total-characters-in-string-after-transformations-ii/) | Hard | Unsolved |
 | May 15 | []() |  |  |
 | May 16 | []() |  |  |
 | May 17 | []() |  |  |
@@ -42,4 +42,4 @@
 | ---    | --- | --- | --- |
 | Easy   | 4 | 4 | 0 |
 | Medium | 7 | 7 | 0 |
-| Hard   | 2 | 1 | 1 |
+| Hard   | 3 | 1 | 2 |

2025-05-May-LeetCoding-Challenge/Total Characters in String After Transformations II.py

@@ -0,0 +1,54 @@
+from itertools import product
+
+
+class Solution:
+    MOD = 10**9 + 7
+
+    def __multiply_matrices(self, mat1: list[list[int]], mat2: list[list[int]]) -> list[list[int]]:
+        p, q, r = len(mat1), len(mat1[0]), len(mat2[0])
+        result = [[0] * r for _ in range(p)]
+        for i, j in product(range(p), range(r)):
+            temp = 0
+            for k in range(q):
+                temp += mat1[i][k] * mat2[k][j]
+            result[i][j] = temp % self.MOD
+        return result
+
+    def __power_matrix(self, matrix: list[list[int]], exp: int) -> list[list[int]]:
+        n = len(matrix)
+        result = [[int(i == j) for j in range(n)] for i in range(n)]
+        while exp > 0:
+            if exp & 1:
+                result = self.__multiply_matrices(result, matrix)
+            matrix = self.__multiply_matrices(matrix, matrix)
+            exp >>= 1
+        return result
+
+    def lengthAfterTransformations(self, s: str, t: int, nums: list[int]) -> int:
+        transform = [[0] * 26 for _ in range(26)]
+        for i in range(26):
+            for shift in range(nums[i]):
+                transform[i][(i + 1 + shift) % 26] += 1
+        transform = self.__power_matrix(transform, t)
+
+        freqs = [[0] * 26]
+        for ch in s:
+            freqs[0][ord(ch) - ord('a')] += 1
+        freqs = self.__multiply_matrices(freqs, transform)
+        return sum(freqs[0]) % self.MOD
+
+
+def main():
+    s = 'abcyy'
+    t = 2
+    nums = [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2]
+    assert Solution().lengthAfterTransformations(s, t, nums) == 7
+
+    s = 'azbk'
+    t = 1
+    nums = [2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2]
+    assert Solution().lengthAfterTransformations(s, t, nums) == 8
+
+
+if __name__ == '__main__':
+    main()