1 files changed, 41 insertions, 0 deletions
diff --git a/challenge-253/sgreen/python/ch-2.py b/challenge-253/sgreen/python/ch-2.py
new file mode 100755
index 0000000000..aad97b55d0
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+++ b/challenge-253/sgreen/python/ch-2.py
@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+
+import json
+import sys
+
+
+def validate_matrix(matrix):
+    # Calculate the size of the matrix
+    rows = len(matrix)
+    cols = len(matrix[0])
+
+    for r in range(0, rows):
+        # Check that all columns are of equal length
+        if len(matrix[r]) != cols:
+            raise ValueError(f'Row {r} has different number of columns')
+
+        # Check all values are 0 or 1
+        if any(True for i in matrix[r] if i not in (0, 1)):
+            raise ValueError(f'Row {r} has a value other than 0 or 1')
+
+        # Check there are no ones zeros after zero.
+        if any(True for c in range(1, cols) if matrix[r][c-1] == 0 and matrix[r][c] == 1):
+            raise ValueError(f'Row {r} has a 1 after 0')
+
+
+def weakest_row(matrix):
+    # Start by validating any issues with the input
+    validate_matrix(matrix)
+
+    # Sort by the rows with the most 1s, followed by a numerical sort
+    return sorted(range(len(matrix)), key=lambda i: sum(matrix[i]))
+
+
+def main(json_string):
+    matrix = json.loads(json_string)
+    result = weakest_row(matrix)
+    print('(' + ', '.join(map(str, result)) + ')')
+
+
+if __name__ == '__main__':
+    main(sys.argv[1])