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65 lines
1.1 KiB
Markdown
65 lines
1.1 KiB
Markdown
# [451. Sort Characters By Frequency](https://leetcode.com/problems/sort-characters-by-frequency/)
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## 题目
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Given a string, sort it in decreasing order based on the frequency of characters.
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Example 1:
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```c
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Input:
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"tree"
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Output:
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"eert"
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Explanation:
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'e' appears twice while 'r' and 't' both appear once.
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So 'e' must appear before both 'r' and 't'. Therefore "eetr" is also a valid answer.
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```
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Example 2:
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```c
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Input:
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"cccaaa"
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Output:
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"cccaaa"
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Explanation:
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Both 'c' and 'a' appear three times, so "aaaccc" is also a valid answer.
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Note that "cacaca" is incorrect, as the same characters must be together.
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```
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Example 3:
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```c
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Input:
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"Aabb"
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Output:
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"bbAa"
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Explanation:
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"bbaA" is also a valid answer, but "Aabb" is incorrect.
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Note that 'A' and 'a' are treated as two different characters.
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```
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## 题目大意
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这道题是 Google 的面试题。
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给定一个字符串，要求根据字符出现的频次从高到低重新排列这个字符串。
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## 解题思路
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思路比较简单，首先统计每个字符的频次，然后排序，最后按照频次从高到低进行输出即可。
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