Ugly Number II

Given an integer n, return the n^th ugly number.

Example 1:

Input: n = 10
Output: 12
Explanation: [1, 2, 3, 4, 5, 6, 8, 9, 10, 12] is the sequence of the first 10 ugly numbers.

Example 2:

Input: n = 1
Output: 1
Explanation: 1 has no prime factors, therefore all of its prime factors are limited to 2, 3, and 5.


Solution

/**

* @param {number} n

* @return {number}

const nthUglyNumber = n => {

const ugly = Array(n);

ugly[0] = 1;

let index2 = 0,

index3 = 0,

index5 = 0;

let factor2 = 2,

factor3 = 3,

factor5 = 5;

for (let i = 1; i < n; i++) {

const min = Math.min(Math.min(factor2, factor3), factor5);

ugly[i] = min;

if (factor2 === min) factor2 = 2 * ugly[++index2];

if (factor3 === min) factor3 = 3 * ugly[++index3];

if (factor5 === min) factor5 = 5 * ugly[++index5];

}

return ugly[n - 1];

};

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