LeetCode-in-All
70. Climbing Stairs
Easy
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 = 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
Constraints:
1 <= n <= 45
Solution
/**
* @param {number} n
* @return {number}
*/
var climbStairs = function(n) {
if (n < 2) {
return n
}
const cache = new Array(n)
cache[0] = 1
cache[1] = 2
for (let i = 2; i < n; i++) {
cache[i] = cache[i - 1] + cache[i - 2]
}
return cache[n - 1]
};
export { climbStairs }