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:
s and give it to the robot. The robot will append this character to the string t.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.
\n\n\n
Example 1:
\n\n\nInput: s = "zza"\nOutput: "azz"\nExplanation: Let p denote the written string.\nInitially p="", s="zza", t="".\nPerform first operation three times p="", s="", t="zza".\nPerform second operation three times p="azz", s="", t="".\n\n\n
Example 2:
\n\n\nInput: s = "bac"\nOutput: "abc"\nExplanation: Let p denote the written string.\nPerform first operation twice p="", s="c", t="ba". \nPerform second operation twice p="ab", s="c", t="". \nPerform first operation p="ab", s="", t="c". \nPerform second operation p="abc", s="", t="".\n\n\n
Example 3:
\n\n\nInput: s = "bdda"\nOutput: "addb"\nExplanation: Let p denote the written string.\nInitially p="", s="bdda", t="".\nPerform first operation four times p="", s="", t="bdda".\nPerform second operation four times p="addb", s="", t="".\n\n\n
\n
Constraints:
\n\n1 <= s.length <= 105s consists of only English lowercase letters.给你一个字符串 s 和一个机器人，机器人当前有一个空字符串 t 。执行以下操作之一，直到 s 和 t 都变成空字符串：
s 的 第一个 字符，并将该字符给机器人。机器人把这个字符添加到 t 的尾部。t 的 最后一个 字符，并将该字符给机器人。机器人将该字符写到纸上。请你返回纸上能写出的字典序最小的字符串。
\n\n\n\n
示例 1：
\n\n输入：s = \"zza\"\n输出：\"azz\"\n解释：用 p 表示写出来的字符串。\n一开始，p=\"\" ，s=\"zza\" ，t=\"\" 。\n执行第一个操作三次，得到 p=\"\" ，s=\"\" ，t=\"zza\" 。\n执行第二个操作三次，得到 p=\"azz\" ，s=\"\" ，t=\"\" 。\n\n\n
示例 2：
\n\n输入：s = \"bac\"\n输出：\"abc\"\n解释：用 p 表示写出来的字符串。\n执行第一个操作两次，得到 p=\"\" ，s=\"c\" ，t=\"ba\" 。\n执行第二个操作两次，得到 p=\"ab\" ，s=\"c\" ，t=\"\" 。\n执行第一个操作，得到 p=\"ab\" ，s=\"\" ，t=\"c\" 。\n执行第二个操作，得到 p=\"abc\" ，s=\"\" ，t=\"\" 。\n\n\n
示例 3：
\n\n输入：s = \"bdda\"\n输出：\"addb\"\n解释：用 p 表示写出来的字符串。\n一开始，p=\"\" ，s=\"bdda\" ，t=\"\" 。\n执行第一个操作四次，得到 p=\"\" ，s=\"\" ，t=\"bdda\" 。\n执行第二个操作四次，得到 p=\"addb\" ，s=\"\" ，t=\"\" 。\n\n\n
\n\n
提示：
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"book": null,
"isSubscribed": false,
"isDailyQuestion": false,
"dailyRecordStatus": null,
"editorType": "CKEDITOR",
"ugcQuestionId": null,
"style": "LEETCODE",
"exampleTestcases": "\"zza\"\n\"bac\"\n\"bdda\"",
"__typename": "QuestionNode"
}
}
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