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
    1
    2
    3
    4
    5
    (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
    1
    2
    -r, --reverse
                 Sort in reverse order.
  • uniq – report or filter out repeated lines in a file
    1
    2
    -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
    1
    2
    grep -P '^([0-9]{3}-|\([0-9]{3}\) )[0-9]{3}-[0-9]{4}$' file.txt
    awk '/^([0-9]{3}-|\([0-9]{3}\) )[0-9]{3}-[0-9]{4}$/' file.txt

    194.转置文件

    https://leetcode-cn.com/problems/transpose-file/
    1
    2
    3
    4
    5
    6
    7
    # Read from the file file.txt and print its transposed content to stdout.
    columns=$(cat file.txt | head -n 1 | wc -w)
    for i in $(seq 1 $columns)
    do
    awk '{print $'''$i'''}' file.txt | xargs
    done