You are climbing a stair case. It takes n steps to reach to the top. Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top? Note: Given n will be a positive integer.
Example 1:
Input: 2
Output: 2
Explanation: There are two ways to climb to the top.
1. 1 step + 1 step
2. 2 steps
Example 2:
Input: 3
Output: 3
Explanation: There are three ways to climb to the top.
1. 1 step + 1 step + 1 step
2. 1 step + 2 steps
3. 2 steps + 1 step
- Dynamic Programming
Simple but slow runtime (no memoization(?))
var climbStairs = function(n) {
if(n === 0) return 0
if(n === 1) return 1
if(n === 2) return 2
else{
return climbStairs(n-1) + climbStairs(n-2)
}
};
Fast vers w memoization
var climbStairs = function(n) {
if(n === 0) return 0
if(n === 1) return 1
if(n === 2) return 2
var arr = [1,2]
for(i = 2; i < n; i++) {
arr[i] = arr[i-1] + arr[i-2]
}
return arr[n-1]
};
Result
- Runtime: 48 ms, faster than 88.17% of JavaScript online submissions for Climbing Stairs.
- Memory Usage: 33.8 MB, less than 84.00% of JavaScript online submissions for Climbing Stairs.