0202-happy-number.ts

function isHappy(n: number): boolean {
    const visit = new Set();

    while (!visit.has(n)) {
        visit.add(n);
        n = sumOfSquares(n);

        if (n == 1) return true;
    }

    return false;
}

function sumOfSquares(n: number): number {
    let output = 0;

    while (n) {
        let digit = n % 10;
        digit = digit ** 2;
        output += digit;
        n = Math.floor(n / 10);
    }

    return output;
}