Educational Codeforces Round 19 C

Description

Petya recieved a gift of a string s with length up to 105 characters for his birthday. He took two more empty strings t and u and decided to play a game. This game has two possible moves:

Extract the first character of s and append t with this character.
Extract the last character of t and append u with this character.

Petya wants to get strings s and t empty and string u lexigraphically minimal.

You should write a program that will help Petya win the game.

Input

First line contains non-empty string s (1 ≤ |s| ≤ 10⁵), consisting of lowercase English letters.

Output

Print resulting string u.

Examples

input

cab

output

abc

input

acdb

output

abdc
题意：第一个字符串的首字母放在第二个字符串的中，第二个字符串的结尾再输出，求能够得到字典序最小的字符串
解法：模拟，如果第一个字符串的首字母为最小，则直接输出，否则压入栈内，处理完毕之后再输出

 #include <bits/stdc++.h>

 using namespace std;

 int num[];

 string s;

 int check(char c)

 {

     for(int i='a';i<c;i++)

     {

         if(num[i])

         {

             return ;

         }

     }

     return ;

 }

 stack<char>q;

 int main() {

     ios::sync_with_stdio(false);

     cin.tie();

     cin>>s;

     for(int i=;i<s.size();i++)

     {

         num[s[i]]++;

     }

     int cnt=;

     while(cnt<s.size())

     {

         if(q.empty())

         {

             q.push(s[cnt]);

             num[s[cnt]]--;

             cnt++;

         }

         else if(check(q.top()))

         {

             cout<<q.top();

             q.pop();

         }

         else

         {

             q.push(s[cnt]);

             num[s[cnt]]--;

             cnt++;

         }

     }

     while(!q.empty())

     {

         cout<<q.top();

         q.pop();

     }

     return ;

 }

巴特西

Educational Codeforces Round 19 C

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