Most efficient method to check for range of numbers within number without duplicates

Question

Given a number n , a minimum number min , a maximum number max , what is the most efficient method to determine

1. Numbe

Answer 1

Solution 1

test using regex

var min = 2;
var max = 7;
res = "";
arr = [81, 35, 22, 45, 49]
arr.push("");
regex=new RegExp("[" + min + "-" + max + "](.)(?!=\1)", "g")
var result = arr.reduce(function(a, b) {
  if (regex.test(a)) {
    res = res + a + " is true\n"
  } else {
    res = res + a + " is false\n"
  };
  return b
});
console.log(res)

The reduce method is different in a sense that it is like a generator function like in python (produces output on the fly)

Its simply loops through each elements in an array using a callback function. I cannot say how efficient is the reduce function.

Nevertheless consider two elements in the array

81                             35          
^
take this value            take the result
and do something           from the previous 
                           element and add it
                           to the result computed
                           for this element  

further information https://msdn.microsoft.com/en-us/library/ff679975%28v=vs.94%29.aspx

SOlution 2

Using list to store value and their boolean

var min = 2;
var max = 7;
res = [""];
arr = [81, 35, 22, 45, 49]
arr.push("");
regex=new RegExp("[" + min + "-" + max + "](.)(?!=\1)", "g")
var result = arr.reduce(function(a, b) {
  if (regex.test(a)) {
    res.push([a,true])
  } else {
    res.push([a,false])
  };
  return b
});
console.log(res)