Climbing Stairs | Problems

You are climbing a staircase with n steps. Each time you can climb 1 or 2 steps. How many distinct ways can you reach the top?

Example: n = 3 → Output: 3 (1+1+1, 1+2, 2+1)

Sample Input

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Sample Output

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Constraints

Test Cases

Case 1

Args: [2] Expected: 2

Case 2

Args: [3] Expected: 3

Case 3

Args: [5] Expected: 8

Topics

Dynamic Programming (Fibonacci)

function climbStairs(n) {
  if (n <= 2) return n;
  let a = 1, b = 2;
  for (let i = 3; i <= n; i++) [a, b] = [b, a + b];
  return b;
}

Time: O(n) | Space: O(1)

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