Ones-and-Zeros

Description

Given an array of ones and zeroes, convert the equivalent binary value to an integer.

Eg: [0, 0, 0, 1] is treated as 0001 which is the binary representation of 1.

Examples

Testing: [0, 0, 0, 1] ==> 1
Testing: [0, 0, 1, 0] ==> 2
Testing: [0, 1, 0, 1] ==> 5
Testing: [1, 0, 0, 1] ==> 9
Testing: [0, 0, 1, 0] ==> 2
Testing: [0, 1, 1, 0] ==> 6
Testing: [1, 1, 1, 1] ==> 15
Testing: [1, 0, 1, 1] ==> 11

However, the arrays can have varying lengths, not just limited to 4.

Solutions

Julia

using Test


"""
二进制各位数字向量转换为10进制数字
"""

#> "二进制各位数字向量转换为10进制数字\n"

function binaryarraytonumber(arr::Vector{Int64})::Int64
    # 解法一：二元函数 (i, x) 的向量化操作
    # [x * 2^(i - 1) for (i, x) ∈ enumerate(reverse(arr))] |> sum

    # 解法二：解析二进制字符串为10进制整数
    parse(Int, join(arr), base=2)
end

#> binaryarraytonumber (generic function with 1 method)

@test binaryarraytonumber([0, 1, 1, 0]) == 6

#> Test Passed
#>   Expression: binaryarraytonumber([0, 1, 1, 0]) == 6
#>    Evaluated: 6 == 6

R

library(tidyverse)

binary2number <- function(arr) {
    # 向量化操作 map2_dbl( .x = rev(arr), .y = 0:(length(arr) - 1), .f =
    # function(x, i) x * 2^i ) %>% sum()

    # 转换 k 进制字符串为 10 进制整数
    str_c(arr, collapse = "") %>%
        strtoi(base = 2L)
}

library(testthat)
test_that("Sample Tests", {
    expect_equal(binary2number(c(0, 1, 1, 0)), 6)
})

#> Test passed 🥳

JavaScript

const sum = require("../src/JavaScript/toolkit/Statistics").sum;


const binaryArrayToNumber = arr => {
  // 向量化操作
  // return sum(arr.reverse().map((x, i) => x * Math.pow(2, i)));

  // 解析2进制字符串为10进制整数
  return parseInt(arr.join(''), 2);
};


console.log(binaryArrayToNumber([0, 1, 1, 0]) == 6);

#> true