Question

How to find the largest prime factor of a number in Node.js

Answer 1

function largestPrimeFactor(n) {
    let div = 2;
    let maxPFact = -1;

    while (n !== 0) {
        if (n % div !== 0) {
            div++;
        } else {
            maxPFact = n;
            n = Math.floor(n / div); // Integer division
            if (n === 1) {
                break;
            }
        }
    }

    return maxPFact;
}

console.log(largestPrimeFactor(13195));  // 5 x 7 x 12 x 29
console.log(largestPrimeFactor(124));  // 2 x 2 x 31
console.log(largestPrimeFactor(288));  // 2 x 2 x 2 x 2 x 2 x 3 x 3
console.log(largestPrimeFactor(1288)); // 2 x 2 x 2 x 7 x 23
console.log(largestPrimeFactor(100000000)); // 2, 2, 2, 2, 2, 2, 2, 2, 5, 5, 5, 5, 5, 5, 5, 5

  
  
/*
run:
 
29
31
3
23
5

*/

 

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