Climb Stairs

Brandon C. Roberts,Last updated at Sun Nov 17 2024•data structures and algorithms

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LeetCode Problem 70

Problem Description

You are climbing a staircase. It takes n steps to reach the top.

Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?

Climbing Stairs Visualizer

Visualize the dynamic programming solution for counting ways to climb stairs

Number of Steps (1-20)

Animation Speed (ms)

one: 1

two: 1

Examples

Example 1:

Input: n = 2 Output: 2 Explanation: There are two ways to climb to the top.

1 step + 1 step
2 steps

Example 2:

Input: n = 3 Output: 3 Explanation: There are three ways to climb to the top.

1 step + 1 step + 1 step
1 step + 2 steps
2 steps + 1 step

Solution

const climbStairs = (n: number): number => {
  let one = 1;
  let two = 1;
 
  for (let i = 0; i < n - 1; i++) {
    const temp = one;
    one = one + two;
    two = temp;
  }
  return one;
};