Package g0401_0500.s0451_sort_characters_by_frequency

Class Solution

  • public class Solution
extends Object
    451 - Sort Characters By Frequency.

    Medium

    Given a string s, sort it in decreasing order based on the frequency of the characters. The frequency of a character is the number of times it appears in the string.

    Return the sorted string. If there are multiple answers, return any of them.

    Example 1:

    Input: s = “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: s = “cccaaa”

    Output: “aaaccc”

    Explanation: Both ‘c’ and ‘a’ appear three times, so both “cccaaa” and “aaaccc” are valid answers. Note that “cacaca” is incorrect, as the same characters must be together.

    Example 3:

    Input: s = “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.

    Constraints:

    • 1 <= s.length <= 5 * 105
    • s consists of uppercase and lowercase English letters and digits.

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail