COMPILER - Editorial

combination of statements

char* a[500];
// ...
a[m][j]

is strange isn’t it?

1 Like

Actually,
i used to work on Turbo c++ and it used to work on it.
and also i am new to codeshef.
But Yes It seems strange,
http://ideone.com/ObhNFA,
its working now but ,
time limit exceed,
but i m trying to develop better logic.

You was kind of lucky, your code is not working on ideone I had to change

Scanner s = new Scanner(System.in);
String str = s.nextLine();

to

//Scanner s = new Scanner(System.in);
String str = rea.nextLine();

and the code returns 0 4 0 for input from problem statement http://ideone.com/UyDMNu , can you fork it and fix it on ideone?

Your code is not working on ideone, can you fix it? http://ideone.com/1AnFUY I used your last submission in practice…

try this test case <<>.The answer should be 0 , but ur code gives 2.

@rishab
why so coz <<> last two brackets are matching which is the case with the official test case of <>>> which gives 2 as output.
plz clarify it :frowning:

you should output the length of the longest prefix

1 Like

thanku got it :stuck_out_tongue:

ad hoc means something that is not known in advance

ANswer for ><<>> should be 0

Why so ?? I can see that I have valid string of length 4 here

Read the problem statement carefully it has asked for length of longest valid ‘prefix’ , so the expression must start with ‘<’. Hope it helps!

They have asked “Prefix”. Read question again. Even first ‘>’ gives answer 0 as there is no valid prefix. There is no need to check further.

https://www.codechef.com/viewsolution/24353005
is my code, please let me know where’s the mistake.
I tried various test cases and they display correct output. I used pair parentheses algorithm to solve it and have then multiplied the count object by 2 to get the output.

Can someone plz point out the mistake here… i do not understand y this is giving WA.
https://www.codechef.com/submit/COMPILER

I am getting the wrong answer, plz explain to me why.

link

#include<bits/stdc++.h>
#define fast ios_base::sync_with_stdio(false); cin.tie(NULL);

using namespace std ;


int main(void){
    stack<char> mystack;
    int t;
    int i=0,ans=0;
    string ch;
    int l;
    cin>>t;
    while(t--){
        ans=0;
        i=0;
        cin>>ch;
        l=ch.size();
        while(l--){
               // cout<<mystack.empty()<<endl;
        if(ch[i]=='<'){
            mystack.push(ch[i]);
            //cout<<"pushing"<<endl;

        }
        else if(!mystack.empty() and ch[i]=='>'){
            mystack.pop();
            //cout<<"poping"<<endl;
            ans+=2;
        }
        else if(mystack.empty() and ch[i]=='>'){
                break;
        }
        i++;
    }
    if(mystack.empty()){
        cout<<ans<<endl;
    }
    else{
            cout<<'0'<<endl;
    }
}
}

i am also trying to find same thing if you get ans plz tell me to

Can someone plz tell me why i am getting WA ! which test case i am missing ?
https://www.codechef.com/viewsolution/26554850

How my solution is wrong ?

> #include<iostream>
> #include<stack>
> #include<vector>
> using namespace std;
> 
> int main()
> {
>     int t;
>     vector<int> ans;
>     cin>>t;
>     while(t--)
>     {
>         stack<char> expr;
>         string str;
>         cin>>str;
>         int sum=0;
>         for(int i=0;i<str.length();i++)
>         {
>             if(str[i]=='<')
>                 expr.push(str[i]);
>             else if(!expr.empty())
>             {
>                 expr.pop();
>                 sum+=2;
>             }
>             else
>                 break;
>         }
>         ans.push_back(sum);
>     }
>     for(auto i=ans.begin();i!=ans.end();i++)
>         cout<<*i<<"\n";
>     return 0;
> }
>

The answer is correct. It should be 0, since there are no "lapin"s at the prefix.

1 Like