451. Sort Characters By Frequency

Given a string, sort it in decreasing order based on the frequency of characters.

Example 1:

Input:
"tree"

Output:
"eert"

Explanation:
'e' appears twice while 'r' and 't' both appear once.
So 'e' must appear before both 'r' and 't'. Therefore "eetr" is also a valid answer.

Example 2:

Input:
"cccaaa"

Output:
"cccaaa"

Explanation:
Both 'c' and 'a' appear three times, so "aaaccc" is also a valid answer.
Note that "cacaca" is incorrect, as the same characters must be together.

Example 3:

Input:
"Aabb"

Output:
"bbAa"

Explanation:
"bbaA" is also a valid answer, but "Aabb" is incorrect.
Note that 'A' and 'a' are treated as two different characters.

# @lc code=start
using LeetCode

function frequency_sort(s::String)
    u_vec = codeunits(s)[:]
    freq = fill(0, 128)
    for n in codeunits(s)
        freq[n] += 1
    end
    sort!(u_vec; by=x -> (freq[x], x), rev = true)
    String(u_vec)
end
# @lc code=end

frequency_sort (generic function with 1 method)

This page was generated using DemoCards.jl and Literate.jl.