70. Climbing Stairs

You climb a staircase of n steps, taking 1 or 2 steps at a time. In how many distinct ways can you reach the top?

Only the previous two values matter, so keep just those.

1function climbStairs(n: number): number {
2  let a = 1, b = 1;
3  for (let i = 2; i <= n; i++) {
4    [a, b] = [b, a + b];
5  }
6  return b;
7}

a = 1b = 1

a = ways(i−2) = 1, b = ways(i−1) = 1.

1 / 0

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