Adding challenge 6.

Author: badprog

p_6_zigzag_conversion/README.md

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+# p_6_zigzag_conversion
+
+🔗 https://leetcode.com/problems/zigzag-conversion/description/?source=submission-noac
+
+## Leetcode - 6 - Zigzag conversion
+
+The string "PAYPALISHIRING" is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)
+
+![alt text](image.png)  
+
+![alt text](image-1.png)
+
+And then read line by line: "PAHNAPLSIIGYIR"  
+
+Write the code that will take a string and make this conversion given a number of rows:
+
+string convert(string s, int numRows);
+ 
+
+Example 1:
+
+Input: s = "PAYPALISHIRING", numRows = 3
+Output: "PAHNAPLSIIGYIR"
+
+Example 2:
+
+Input: s = "PAYPALISHIRING", numRows = 4
+Output: "PINALSIGYAHRPI"
+Explanation:
+
+![alt text](image-2.png)
+
+Example 3:
+
+Input: s = "A", numRows = 1
+Output: "A"
+ 
+
+Constraints:
+
+1 <= s.length <= 1000  
+s consists of English letters (lower-case and upper-case), ',' and '.'.  
+1 <= numRows <= 1000  

p_6_zigzag_conversion/image-1.png

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+# https://github.com/badprog/badprog_leetcode_python
+
+################
+# import
+import sys
+import pathlib
+
+# Adding the parent directory of this file to the sys.path
+sys.path.append(str(pathlib.Path(__file__).resolve().parents[1]))
+
+from src.solution import Solution
+from typing import List
+
+################
+#
+def main():
+    print("Hello from Badprog, Leetcode challenge 6 and Python :D")
+    solution = Solution()
+    # s = "PAYPALISHIRING"
+    s = "AB"
+    num_rows = 1
+    result = solution.convert(s, num_rows)
+    print("result = {}", result)
+    
+################
+#
+if __name__ == "__main__":
+    main()
+

p_6_zigzag_conversion/image-2.png

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+# https://github.com/badprog/badprog_leetcode_python
+
+from typing import List
+
+############################
+#
+class Solution:
+    ############################
+    #
+    def convert(self, s: str, numRows: int) -> str:
+        #
+        if numRows == 1:
+            return s
+        
+        #
+        vec_row: List[str] = [""] * numRows
+        step = 0
+        cur_row = 0
+        
+        for index, element in enumerate(s):
+            # print(f"index: {index}, element: {element}")
+            vec_row[cur_row] += element
+            
+            if cur_row == 0:
+                step = 1
+            elif cur_row == numRows - 1:
+                step = -1
+        
+            cur_row += step
+            
+        #
+        # print(f"vec_row: {vec_row}")
+        final_str = ''.join(vec_row)
+        
+        #
+        return final_str
+    

p_6_zigzag_conversion/image.png

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+# https://github.com/badprog/badprog_leetcode_python
+
+############################
+# import
+import sys
+import pathlib
+
+# Adding the parent directory of this file to the sys.path
+sys.path.append(str(pathlib.Path(__file__).resolve().parents[1]))
+
+import pytest
+from src.solution import Solution
+
+def test_standard_case_numRows_3():
+    solution = Solution()
+    assert solution.convert("PAYPALISHIRING", 3) == "PAHNAPLSIIGYIR"
+
+def test_standard_case_numRows_4():
+    solution = Solution()
+    assert solution.convert("PAYPALISHIRING", 4) == "PINALSIGYAHRPI"
+
+def test_single_row():
+    solution = Solution()
+    assert solution.convert("A", 1) == "A"
+
+def test_short_string_numRows_2():
+    solution = Solution()
+    assert solution.convert("AB", 2) == "AB"
+
+def test_string_numRows_2():
+    solution = Solution()
+    assert solution.convert("ABCDE", 2) == "ACEBD"
+
+def test_numRows_greater_than_string_length():
+    solution = Solution()
+    assert solution.convert("ABC", 5) == "ABC"
+
+def test_empty_string():
+    solution = Solution()
+    assert solution.convert("", 3) == ""
+
+def test_zigzag_numRows_3():
+    solution = Solution()
+    assert solution.convert("ABCDEFGHI", 3) == "AEIBDFHCG"
+
+def test_zigzag_numRows_5():
+    solution = Solution()
+    assert solution.convert("ABCDEFGHIJK", 5) == "AIBHJCGKDFE"  # Fixed expected output
+
+def test_special_characters():
+    solution = Solution()
+    assert solution.convert("Hello,World!", 3) == "Horel,ol!lWd"  # Fixed expected output