linux shell（leetcode）

194 Transpose File（leetcode）

https://leetcode.com/problems/transpose-file/

解析参考：http://www.cnblogs.com/grandyang/p/5382166.html

---

file.txt (2行3列)

name age
alice 21
ryan 30

---

awk '{
    for (i = 1; i <= NF; ++i) {
        printf("%d ",i);
    }
}' file.txt

打印出 1 2 1 2 1 2
说明 执行了3次for，每次for 循环两次（NF表示列数，有两列）

---

$1 可以打印第一列的值，$2可以打印第2列的值

用一个数组 s[1]存第一列，s[2]存第二列

awk '{
    for (i = 1; i <= NF; ++i) {
        if(NR == 1)
                s[i] = $i;
        else
                s[i] = s[i] " " $i;
    }
}
END{
        for(i = 1; i <= NF; ++i)
                printf("%s\n", s[i]);
}' file.txt

实现转置 打印出
name alice ryan
age 21 30

---

192 Word Frequency

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

words.txt

the day is sunny the the
the sunny is is

output(sorted by descending frequency)

the 4
is 3
sunny 2
day 1

ac

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

参考：
在线疯狂
http://bookshadow.com/weblog/2015/03/24/leetcode-word-frequency/

主要命令

tr / sed
sort
uniq
awk

---