exercise file and solution for max nested

Author: learnbyexample

exercise_files/q6c_max_nested.py

@@ -0,0 +1,42 @@
+#!/usr/bin/python3
+
+def max_nested_braces(expr):
+    pass
+
+assert max_nested_braces('a*b') == 0
+assert max_nested_braces('a*b{') == -1
+assert max_nested_braces('a*{b+c}') == 1
+assert max_nested_braces('{a+2}*{b+c}') == 1
+assert max_nested_braces('a*{b+c*{e*3.14}}') == 2
+assert max_nested_braces('a*{b+c*{e*3.14}}}') == -1
+assert max_nested_braces('a*{b+c}}') == -1
+assert max_nested_braces('a*b+{}') == 1
+assert max_nested_braces('}a+b{') == -1
+assert max_nested_braces('{{a+2}*{b+c}+e}') == 2
+assert max_nested_braces('{{a+2}*{b+{c*d}}+e}') == 3
+assert max_nested_braces('{{a+2}*{{b+{c*d}}+e*d}}') == 4
+assert max_nested_braces('{{a+2}*{{b}+{c*d}}+e*d}}') == -1
+
+print('all tests passed')
+
+
+#### alternate using regular expressions
+
+#import re
+#
+#def max_nested_braces(expr):
+#    count = 0
+#    while True:
+#        expr_sub = re.sub(r'\{[^{}]*\}', '', expr)
+#        if expr_sub == expr:
+#            break
+#        count += 1
+#        expr = expr_sub
+#
+#    if re.search(r'[{}]', expr):
+#        return -1
+#    return count
+
+# for bonus, use + instead of *
+#assert max_nested_braces('a*b+{}') == -1
+#assert max_nested_braces('a*{b+{}+c*{e*3.14}}') == -1

exercise_solutions/q6c_max_nested.py

@@ -0,0 +1,55 @@
+#!/usr/bin/python3
+
+def max_nested_braces(expr):
+    max_count = count = 0
+    for char in expr:
+        if char == '{':
+            count += 1
+            if count > max_count:
+                max_count = count
+        elif char == '}':
+            if count == 0:
+                return -1
+            count -= 1
+
+    if count != 0:
+        return -1
+    return max_count
+
+assert max_nested_braces('a*b') == 0
+assert max_nested_braces('a*b{') == -1
+assert max_nested_braces('a*{b+c}') == 1
+assert max_nested_braces('{a+2}*{b+c}') == 1
+assert max_nested_braces('a*{b+c*{e*3.14}}') == 2
+assert max_nested_braces('a*{b+c*{e*3.14}}}') == -1
+assert max_nested_braces('a*{b+c}}') == -1
+assert max_nested_braces('a*b+{}') == 1
+assert max_nested_braces('}a+b{') == -1
+assert max_nested_braces('{{a+2}*{b+c}+e}') == 2
+assert max_nested_braces('{{a+2}*{b+{c*d}}+e}') == 3
+assert max_nested_braces('{{a+2}*{{b+{c*d}}+e*d}}') == 4
+assert max_nested_braces('{{a+2}*{{b}+{c*d}}+e*d}}') == -1
+
+print('all tests passed')
+
+
+#### alternate using regular expressions
+
+#import re
+#
+#def max_nested_braces(expr):
+#    count = 0
+#    while True:
+#        expr_sub = re.sub(r'\{[^{}]*\}', '', expr)
+#        if expr_sub == expr:
+#            break
+#        count += 1
+#        expr = expr_sub
+#
+#    if re.search(r'[{}]', expr):
+#        return -1
+#    return count
+
+# for bonus, use + instead of *
+#assert max_nested_braces('a*b+{}') == -1
+#assert max_nested_braces('a*{b+{}+c*{e*3.14}}') == -1