Leetcode no. 192

192. Word Frequency

Write a bash script to calculate the frequency of each word in a text file words.txt.

For simplicity sake, you may assume:

• words.txt contains only lowercase characters and space ' ' characters.
• Each word must consist of lowercase characters only.
• Words are separated by one or more whitespace characters.

For example, assume that words.txt has the following content:

the day is sunny the the
the sunny is is

Your script should output the following, sorted by descending frequency:

the 4
is 3
sunny 2
day 1

Note:
Don't worry about handling ties, it is guaranteed that each word's frequency count is unique.

# Read from the file words.txt and output the word frequency list to stdout.
cat words.txt | tr -s ' ' '\n' | sort | uniq -c | sort -r | awk '{print $2,$1}'

或者

awk '{for (i=1; i<=NF; i++){++D[$i];}} END {for(i in D){print i, D[i]}}' words.txt | sort -nr -k 2