bolt_tech_interview_1.js

const _ = require('lodash');

/**
Write a function checking that the given string is valid. We consider a string to be valid if all the characters of the string have exactly the same frequency.

Examples:
"aabbcc" is a valid string
"aabbccc" is an invalid string
*/

function stringIsValid(input: string) : boolean {
  
  const map = {};
  
  for( let i = 0; i < input.length; i++){
    // O(1)
    map[input[i]] = (map[input[i]] || 0) + 1;
  }
  
  const set = new Set(Object.values(map));
  
  const keysSet = new Set(Object.keys(map));
  
  if(set.size !== keysSet.size)
    return false;
  
  if(set.size === 1)
    return true;
  
  if(set.size > 2)
    return false;
  
  let smallerOne;
  let biggerOne;
  
  if(set[0] > set[1]){
    biggerOne = 0; 
    smallerOne = 1;
  }else{
    biggerOne = 1;
    smallerOne = 0;
  }
  
  const setValues = Array.from(set) as number[];
  
  
  if(setValues[biggerOne] - 1 !== setValues[smallerOne])
    return false;
   
  return true;
  
}

const samples = [
  { text: "aabbcc", expect: true},
  { text: "aabbba", expect: true},
  { text: "aabbccc", expect: true},
  { text: "aabbcccddd", expect: false},
]


for(let sample of samples){
  
  if(stringIsValid(sample.text) !== sample.expect){
    throw new Error("invalid string: " + sample.text);
  }
  
}

console.log('Finished');


// time complexity: O(n)
// space complexity: O(n)

// aabbcc

// aabbba