Minimum Bracket Reversal

netsetos · web-flow · commit c8b93336e4eb · 2020-06-22T20:08:35.000+05:30
Initial File
diff --git a/Minimum Bracket Reversal b/Minimum Bracket Reversal
@@ -0,0 +1,23 @@
+def min_bracket_reversal(exp):
+    size=len(exp)
+    if size%2!=0:
+        return None
+    s=[]
+    for i in range(size):
+        if exp[i]=='}' and len(s)>0:
+            if s[0] == '{':
+                s.pop(0)
+            else:
+                s.insert(0,exp[i])
+        else:
+            s.insert(0,exp[i])
+
+    total_left = len(s)
+    open=0
+    while( len(s)>0 and s[0] == '{'):
+        s.pop(0)
+        open=open+1
+    return total_left//2 + open % 2
+
+expr = "{{}{{}{{"
+print(min_bracket_reversal(expr))
