JS | Arrays | Find Common Characters | Interview Question

Super East Solution

Given a string array words, return an array of all characters that show up in all strings within the words (including duplicates). You may return the answer in any order.

Input: words = ["bella","label","roller"]
Output: ["e","l","l"]
- Get intersection of string with duplicates. At a minimum all characters must share a min frequency.

Solution, O(n)

const findCommonCharacters = (str1, str2) => {
  let commonChars= "";
  const obj1 = {};
  for (let key of str1) {
    if (obj1[key]) {
      obj1[key] = obj1[key] + 1
    } else {
     obj1[key] = 1
    }
  }
  
  for (let key of str2) {
    if (obj1[key] > 0) {
     commonChars = commonChars + key;
    }
  } 
 return commonChars
}
const getCommonCharacters = (words) => {
  if(words.length === 0) return [];
  let commonCharacters = words[0];
  
  
  for (let i = 1; i < words.length; i++) {
   if (commonCharacters !== words[i]) {
     commonCharacters = findCommonCharacters(words[i], commonCharacters)
    }
  }
  
  return commonCharacters;
}
const words = ["bella","label","roller"];
console.log(getCommonCharacters(words));

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