#2434
Using a Robot to Print the Lexicographically Smallest String
medium · verified · 62.5% accepted · 1,153 likes · top 64%
hash table · string · stack · greedy
Description
You are given a string s and a robot that currently holds an empty string t. Apply one of the following operations until s and t are both empty:
- Remove the first character of a string s and give it to the robot. The robot will append this character to the string t.
- Remove the last character of a string t and give it to the robot. The robot will write this character on paper.
Return the lexicographically smallest string that can be written on the paper.
Example 1:
Input: s = "zza"
Output: "azz"
Explanation: Let p denote the written string.
Initially p="", s="zza", t="".
Perform first operation three times p="", s="", t="zza".
Perform second operation three times p="azz", s="", t="".
Example 2:
Input: s = "bac"
Output: "abc"
Explanation: Let p denote the written string.
Perform first operation twice p="", s="c", t="ba".
Perform second operation twice p="ab", s="c", t="".
Perform first operation p="ab", s="", t="c".
Perform second operation p="abc", s="", t="".
Example 3:
Input: s = "bdda"
Output: "addb"
Explanation: Let p denote the written string.
Initially p="", s="bdda", t="".
Perform first operation four times p="", s="", t="bdda".
Perform second operation four times p="addb", s="", t="".
Solution