Merge pull request #202 from Hitanshu123/master

Remove Superfluous Brackets in Expression

Author: probot-auto-merge[bot]

Remove Superfluous Brackets.txt

@@ -0,0 +1,102 @@
+#include<bits/stdc++.h>
+using namespace std ;
+int priority(char c)
+{
+    if(c=='*' || c=='/')
+        return 1;
+    else if(c=='+' || c=='-')
+        return 2;
+}
+bool isOperator(char c)
+{
+    if(c == '+' || c=='-' || c=='*' || c=='/')
+        return true ;
+    else
+        return false ;
+}
+string Rem_superfluous(string s)
+{
+    stack<string> st ;
+    for(int i=0;i<s.size();i++)
+    {
+        if(!isOperator(s[i])){
+                string x(1,s[i]) ;
+            st.push(x) ;
+        }
+        else
+        {
+            string s2 = st.top() ;
+            st.pop() ;
+            string s1 = st.top() ;
+            st.pop() ;
+            string x ;
+            string ch(1,s[i]) ;
+            if(priority(s[i])==1 || i==s.size()-1)
+                x = s1+ch+s2;
+            else if(priority(s[i])==2)
+                x = "("+s1+ch+s2+")";
+            st.push(x) ;
+        }
+    }
+    if(st.size() == 1){
+            return st.top() ;
+        }
+}
+string infix_to_postfix(string s)
+{
+    s = "("+s+")" ;
+    stack<char> st ;
+    string ans = "" ;
+    for(int i=0;i<s.size();i++)
+    {
+        if(s[i] == '(')
+            st.push(s[i]) ;
+        else if(!isOperator(s[i]) && s[i] != ')')
+        {
+            string x(1,s[i]);
+            ans+=x;
+        }
+        else if(isOperator(s[i]))
+        {
+            char x = st.top() ;
+            if(isOperator(x))
+            {
+                if(priority(x)<priority(s[i]))
+                {
+                    string ch(1,x);
+                    ans+=ch ;
+                    st.pop() ;
+                    st.push(s[i]);
+                }
+                else
+                {
+                    st.push(s[i]);
+                }
+            }
+            else
+                st.push(s[i]);
+        }
+        else if(s[i] == ')')
+        {
+            while(st.top() != '(')
+            {
+                char x = st.top() ;
+                string ch(1,x) ;
+                ans+=ch ;
+                st.pop() ;
+            }
+            st.pop() ;
+        }
+    }
+
+    return ans ;
+}
+int main()
+{
+    string s1 ;
+    cout<<"Enter the Postfix Expression : ";
+    cin>>s1 ;
+    string ans = Rem_superfluous(infix_to_postfix(s1)) ;
+    cout<<endl<<"Output :-  "<<ans<<endl ;
+    return 0 ;
+}