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Climbing Stairs

Problem statement​

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?

Example 1:

Input: n = 2Output: 2Explanation: There are two ways to climb to the top.1. 1 step + 1 step2. 2 steps

Example 2:

Input: n = 3Output: 3Explanation: There are three ways to climb to the top.1. 1 step + 1 step + 1 step2. 1 step + 2 steps3. 2 steps + 1 step

Constraints:

  • 1 <= n <= 45

My solution​

/**
 * @param {number} n
 * @return {number}
 */
var climbStairs = function(n) {
    const pos = [0, 1, 2]
    
    for (let i = 3; i <= n; i++) {
        pos[i] = pos[i - 1] + pos[i - 2]
    }
    
    return pos[n]
};