192.统计词频

https://leetcode-cn.com/problems/word-frequency/

1
cat words.txt | tr -s ' ' '\n' | sort | uniq -c | sort -r | awk '{print $2, $1}'

命令说明:(man cmd)

  • cat – concatenate(link (things) together in a chain or series) and print files
    1
    (The cat utility reads files sequentially, writing them to the standard output.)
  • tr – translate characters
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    2
    3
    4
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    (The tr utility copies the standard input to the standard output with sub-stitution or deletion of selected characters.)
    (-s Squeeze multiple occurrences of the characters listed in the last
    operand (either string1 or string2) in the input into a single
    instance of the character. This occurs after all deletion and
    translation is completed.)
  • sort – sort or merge records (lines) of text and binary files
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    -r, --reverse
    Sort in reverse order.
  • uniq – report or filter out repeated lines in a file
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    -c      Precede each output line with the count of the number of times
    the line occurred in the input, followed by a single space.
  • awk - pattern-directed scanning and processing language(很强大,只用他也能完成这个任务,不过如果是只用这个的话,也可以用编写起来更趁手的python或者node来处理了)

分词这一步tr -s ' ' '\n'也可以替换成xargs -n1

193.有效电话号码

https://leetcode-cn.com/problems/valid-phone-numbers/

  • 分析正则
  • 使用grep/awk/gawk都可