Jun 17

Author: siddydutta

2025-06-June-LeetCoding-Challenge/Count the Number of Arrays with K Matching Adjacent Elements.py

@@ -0,0 +1,24 @@
+from math import comb
+
+
+class Solution:
+    MOD = 10**9 + 7
+
+    def countGoodArrays(self, n: int, m: int, k: int) -> int:
+        return (comb(n - 1, k) * m * pow(m - 1, n - k - 1, self.MOD)) % self.MOD
+
+
+def main():
+    n = 3
+    m = 2
+    k = 1
+    assert Solution().countGoodArrays(n, m, k) == 4
+
+    n = 4
+    m = 2
+    k = 2
+    assert Solution().countGoodArrays(n, m, k) == 6
+
+
+if __name__ == '__main__':
+    main()

2025-06-June-LeetCoding-Challenge/README.md

@@ -20,7 +20,7 @@
 | June 14 | []() |  |  |
 | June 15 | []() |  |  |
 | June 16 | [2016. Maximum Difference Between Increasing Elements](https://leetcode.com/problems/maximum-difference-between-increasing-elements/) | Easy | Solved |
-| June 17 | []() |  |  |
+| June 17 | [3405. Count the Number of Arrays with K Matching Adjacent Elements](https://leetcode.com/problems/count-the-number-of-arrays-with-k-matching-adjacent-elements/) | Hard | Unsolved |
 | June 18 | []() |  |  |
 | June 19 | []() |  |  |
 | June 20 | []() |  |  |
@@ -41,4 +41,4 @@
 | ---    | --- | --- | --- |
 | Easy   | 3 | 3 | 0 |
 | Medium | 7 | 4 | 3 |
-| Hard   | 4 | 2 | 2 |
+| Hard   | 5 | 2 | 3 |