SDE - 1

SIMPLE APPROACH USING FAST AND SLOW POINTER APPROACH:

EXPLAINATION USING RACE EXAMPLE:

We can simply consider two cars, one is moving fast and one is moving slow, there's no, point that a slow car can met the fast car at any point of time except start and end.

If they anyhow met that means it's a lap race, and at that moment the slow car and fast car, will be at a certain place.

And now we know how it works.



bool detectLoop(Node* head) {
// Here both cars currently at the start point of the race.
Node*slowCar = head, *fastCar = head;

// CHECKING IF THE RACE IS SINGLE LAP RACE OR NOT.
while(fastCar != NULL && fastCar->next != NULL) {
// MOVING FAST CAR BY TWO STEPS AND SLOW CAR BY ONE.
slowCar = slowCar->next, fastCar = fastCar->next->next;
// IF SOMEHOW THEY MET THEN it is a multiple lap race.
if(fastCar==slowCar) return true;
}
// If they didn't met that means it was a single lap race.
return false;
}

Tip 1:Be calm 
Tip 2:Don't Fake Infront of HR about your Strength and Weakness.
Tip 3:Try to ask questions about the Tech stack on which company is currently working.