Merge pull request #9 from codewithme-py/feat/zigzag-conversion-0006

problem solution & test 0006

Author: codewithme-py

problems_cache.json

@@ -19148,5 +19148,40 @@
     "Longest Alternating Subarray After Removing At Most One Element",
     "Hard",
     "longest-alternating-subarray-after-removing-at-most-one-element"
+  ],
+  "4210": [
+    "Median of a Binary Search Tree Level",
+    "Medium",
+    "median-of-a-binary-search-tree-level"
+  ],
+  "4227": [
+    "Find Users with Persistent Behavior Patterns",
+    "Hard",
+    "find-users-with-persistent-behavior-patterns"
+  ],
+  "4214": [
+    "Count Dominant Indices",
+    "Easy",
+    "count-dominant-indices"
+  ],
+  "4213": [
+    "Merge Adjacent Equal Elements",
+    "Medium",
+    "merge-adjacent-equal-elements"
+  ],
+  "4211": [
+    "Count Subarrays With Cost Less Than or Equal to K",
+    "Medium",
+    "count-subarrays-with-cost-less-than-or-equal-to-k"
+  ],
+  "4202": [
+    "Maximum Score Using Exactly K Pairs",
+    "Hard",
+    "maximum-score-using-exactly-k-pairs"
+  ],
+  "4228": [
+    "Delayed Count of Equal Elements",
+    "Medium",
+    "delayed-count-of-equal-elements"
   ]
 }

solutions/zigzag_conversion_0006.py

@@ -0,0 +1,30 @@
+class Solution:
+    def convert(self, s: str, numRows: int) -> str:
+        """
+        Reformat string s in zigzag pattern with numRows rows,
+        and then read it line by line.
+        Args:
+            s: Input string
+            numRows: Number of rows
+        Returns:
+            Reformatted string
+        Examples:
+            >>> sol = Solution()
+            >>> sol.convert("PAYPALISHIRING", 3)
+            'PAHNAPLSIIGYIR'
+            >>> sol.convert("PAYPALISHIRING", 4)
+            'PINALSIGYAHRPI'
+            >>> sol.convert("A", 1)
+            'A'
+        """
+        if numRows == 1:
+            return s
+        rows = ['' for _ in range(numRows)]
+        current_row = 0
+        direction = 1
+        for i in range(len(s)):
+            rows[current_row] += s[i]
+            current_row += direction
+            if current_row == 0 or current_row == numRows - 1:
+                direction *= -1
+        return ''.join(rows)

tests/test_zigzag_conversion_0006.py

@@ -0,0 +1,13 @@
+import pytest
+
+from solutions.zigzag_conversion_0006 import Solution
+
+
+@pytest.mark.parametrize('s, num_rows, expected', [
+    ('PAYPALISHIRING', 3, 'PAHNAPLSIIGYIR'),
+    ('PAYPALISHIRING', 4, 'PINALSIGYAHRPI'),
+    ('A', 1, 'A'),
+])
+def test_solution(s: str, num_rows: int, expected: str) -> None:
+    sol = Solution()
+    assert sol.convert(s, num_rows) == expected