Method isHappy

Two Pointers/202. Happy Number/Solution.cpp:28–39

two pointer

    
    // two pointer
    bool isHappy(int n) {
        if (n <= 0) return false;
        int slow = next(n);
        int fast = next(slow);
        while (true) {
            if (fast == slow) break;
            slow = next(slow);
            fast = next(next(fast));
            if (fast == 1) return true;
        }
        return fast == 1 ? true : false;
    }
};

int main() {