Descending-Order

Description

Your task is to make a function that can take any non-negative integer as an argument and return it with its digits in descending order. Essentially, rearrange the digits to create the highest possible number.

Examples

Input: 42145 Output: 54421

Input: 145263 Output: 654321

Input: 123456789 Output: 987654321

Solutions

Julia

## Descending-Order.jl

using Pipe, Test


"""
使n的各位数字降序排列
"""

#> "使n的各位数字降序排列\n"

function descending_order(n::Int)::Int
    @pipe n |> string |> collect |> sort |> reverse |> join |> parse(Int64, _)
end

#> descending_order (generic function with 1 method)

@test descending_order(42145) == 54421

#> Test Passed
#>   Expression: descending_order(42145) == 54421
#>    Evaluated: 54421 == 54421

R

library(tidyverse)

#' 整数各位数字降序排列
#' @param n 整数
#' @return 整数
descending_order <- function(n) {
  n %>%
    as.character() %>%
    str_split("") %>% # 注意，该函数返回列表
    unlist() %>%
    sort(decreasing = TRUE) %>% # 可直接对字符排序
    str_c(collapse = "") %>%
    as.integer()
}

descending_order(42145) # 54421

#> [1] 54421

JavaScript

/**
 * 
 * @param {Number} n 
 * @returns {Number}
 */
function descendingOrder(n) {
  return parseInt(String(n).split('').sort().reverse().join(''));
}


// 同理有
function squareDigits(n) {
  return parseInt(String(n).split('').map(x => x ** 2).join(''));
}
console.log(squareDigits(9812) === 816414);


module.exports = descendingOrder;

#> true