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climbing-stairs.js
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climbing-stairs.js
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/*
* [70] Climbing Stairs
*
* https://leetcode.com/problems/climbing-stairs/description/
*
* algorithms
* Easy (41.90%)
* Total Accepted: 279.8K
* Total Submissions: 667.9K
* Testcase Example: '2'
*
* 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
*
*
*/
/**
* @param {number} n
* @return {number}
*/
var climbStairs = function(n) {
n = ~~n
if (n < 0) {
return 0
} else if (n <= 1) {
return 1
} else if (n <= 2) {
return 2
}
let n1 = 1
let n2 = 2
let target = 0
for (let i = 3; i <= n; i++) {
target = n1 + n2
n1 = n2
n2 = target
}
return target
}