harmlessRansomNote.js

/*-----------------------------------------------------------------------------
1.check if the 1st argument's words is existing at the 2nd argument.
2.the function is used to check if the latter is more apples than the former.

the reference is from UdemyCourse: LearningAlgorithmsInJavascriptFromScratch
-----------------------------------------------------------------------------*/

/*＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊

NOTES：Time complexity, Big O notation（）

Big O notation到底資料的增加是讓時間等比例增加還是指數增加…？

O(1)      Constant
O(n)      Linear runtime
O(n^2)    Exponential runtime, such as two time recursives
O(log n)  Logarithmic runtime, like binary search

＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊*/


function harmlessRansomNote(noteText, magazineText) {
  var noteArr = noteText.split(" ");
  var magazineArr = magazineText.split(" ");
  
  // build a dictionary
  var magObj = {}; 
  magazineArr.forEach(word => {
    if (!magObj[word]) {
      magObj[word] = 0;
    }
    magObj[word]++;
  });
  
  // burn a dictionary
  var noteIsFound = true;
  noteArr.forEach(word => {
    if (magObj[word]) {
      magObj[word]--;
      if (magObj[word] < 0) noteIsFound = false;
    } else {
      noteIsFound = false;
    }
  });
  return noteIsFound;
}
var note1 = "This is an apple";
var note2 = "This apple is really sweety apple";
var mag = "the apple on the tree this is an immature apple.";
harmlessRansomNote(note1, mag);