简单思路：动态规划的简单问题，我们爬楼梯到三楼的可能次数是到一楼和到二楼的可能次数，以此类推
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
/**
* @param {number} n
* @return {number}
*/
var climbStairs = function (n) {
if (n === 1 || n === 2) return n;
let i = 1;
let j = 2;
let sum = 0;
for (let index = 3; index <= n; index++) {
sum = i + j;
i = j;
j = sum;
}
return sum;
};
console.log(climbStairs(6));
