Add day21.py - Diamond Pattern

PatternChalange(PYTHON)/day21.py

@@ -0,0 +1,30 @@
+# Day 21: Diamond Pattern
+# Author: Ruchir Ganatra (github.com/Ranchiro)
+# A Python program to print a diamond pattern
+
+def print_diamond(n):
+    """Print a diamond pattern of given size n"""
+    # Upper half of diamond
+    for i in range(1, n + 1):
+        print(' ' * (n - i) + '*' * (2 * i - 1))
+
+    # Lower half of diamond
+    for i in range(n - 1, 0, -1):
+        print(' ' * (n - i) + '*' * (2 * i - 1))
+
+if __name__ == "__main__":
+    size = 5
+    print(f"Diamond Pattern (size={size}):")
+    print_diamond(size)
+    print()
+
+    # Example output for size=5:
+    #     *
+    #    ***
+    #   *****
+    #  *******
+    # *********
+    #  *******
+    #   *****
+    #    ***
+    #     *