/**
 * @param {number} n
 * @return {number}
 */
var climbStairs = function(n) {
    if(n <= 2) {
        return n
    }

    let dp = new Array(n + 1)
    dp[1] = 1
    dp[2] = 2

    for(let i = 3; i <= n; i++) {
        dp[i] = dp[i - 1] + dp[i - 2]
    }

    return dp[n]
};
