add math method

1 files changed, 14 insertions, 7 deletions

diff --git a/challenge-117/steven-wilson/python/ch-1.py b/challenge-117/steven-wilson/python/ch-1.py
index a3870ba254..9978605acd 100755
--- a/challenge-117/steven-wilson/python/ch-1.py
+++ b/challenge-117/steven-wilson/python/ch-1.py
@@ -7,11 +7,18 @@ if __name__ == "__main__":
     file = open(filename)
     lines = file.readlines()
     line_numbers = [int(line.split(',')[0]) for line in lines]
-    line_numbers.sort()
-    number = 1
-    for line_number in line_numbers:
-        if number != line_number:
-            break
-        else:
-            number += 1
+    # Math method
+    sum_of_line_numbers = sum(line_numbers)
+    sum_of_range = sum(range(1, (len(line_numbers) + 2)))
+    number = sum_of_range - sum_of_line_numbers
+
+    # Iterative method
+#     line_numbers.sort()
+#     number = 1
+#     for line_number in line_numbers:
+#         if number != line_number:
+#             break
+#         else:
+#             number += 1
+
     print("The missing row number is %d" % number)
\ No newline at end of file