Super Ugly Numbers JavaScript



Super Ugly Number

Super ugly numbers are positive numbers whose all prime factors are in the given prime list primes of size k. For example, [1, 2, 4, 7, 8, 13, 14, 16, 19, 26, 28, 32] is the sequence of the first 12 super ugly numbers given primes = [2, 7, 13, 19] of size 4.

Problem

We are required to write a JavaScript function that takes in number, num, as the first argument and an array, arr, of prime numbers as the second argument. The function should find and return the (num)th super ugly number.

Example

The code for this will be −

const num = 7;
const arr = [2, 7, 14, 19];
const superUgly = (num = 1, arr = []) => {
   arr.sort((a, b)=> a - b);
   const ptr = [];
   const res = [];
   for(let i=0;i<arr.length;i++){
      ptr[i] = 0;
   };
   res.push(1);
   for(let i = 1; i < num; i++){
      let mn=Math.pow(2, 32) - 1;
      for(let j = 0; j < arr.length; j++){
         mn=Math.min(mn,arr[j]*res[ptr[j]])
      };
      res[i]=mn
      for(let j=0; j < arr.length; j++){
         if(mn % arr[j] === 0){
            ptr[j]++;
         };
      };
   };
   return res[num-1]
};
console.log(superUgly(num, arr));

Output

And the output in the console will be −

16

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