Codeforces 797C

C. Minimal string

题目链接：http://codeforces.com/problemset/problem/797/C

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

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
题目大意：略。
方法：栈顶的优先级大于后缀的优先级，则出栈。
代码：

#include<iostream>
#include<cstdio>
#include<cstring>
#include<stack>
using namespace std;
const int N=1e5+5;
int main()
{
    char s[N];
    gets(s);
    int n=strlen(s);
    char best[N];
    best[n]='z';
    for(int i=n-1;i>=0;i--)
    {
        best[i]=min(best[i+1],s[i]);
    }
    stack<char>v;
    int cur=0;
    while(!v.empty()||cur<n)
    {
        if(!v.empty()&&v.top()<=best[cur])
        {
            putchar(v.top());
             v.pop();
        }
        else v.push(s[cur++]);
    } 
    cout<<endl;
    return 0;
}