feat: add Climbing Stairs

Author: dukeluo

README.md

@@ -79,6 +79,7 @@ Roadmap: https://neetcode.io/roadmap
 | 79   | [Word Search](https://leetcode.com/problems/word-search/)                                                                                                         | Medium     | [ts](./TypeScript/79.word-search.ts)                                                          | Backtracking     |
 | 131  | [Palindrome Partitioning](https://leetcode.com/problems/palindrome-partitioning/description/)                                                                     | Medium     | [ts](./TypeScript/131.palindrome-partitioning.ts)                                             | Backtracking     |
 | 17   | [Letter Combinations of a Phone Number](https://leetcode.com/problems/letter-combinations-of-a-phone-number/description/)                                         | Medium     | [ts](./TypeScript/17.letter-combinations-of-a-phone-number.ts)                                | Backtracking     |
+| 70   | [Climbing Stairs](https://leetcode.com/problems/climbing-stairs/description/)                                                                                     | Easy       | [ts](./TypeScript/70.climbing-stairs.ts)                                                      | 1-D DP           |
 
 ### Others
 

TypeScript/70.climbing-stairs.ts

@@ -0,0 +1,14 @@
+function climbStairs(n: number): number {
+  let one = 1;
+  let two = 1;
+
+  for (let i = 0; i < n - 1; i++) {
+    let temp = one;
+    one = one + two;
+    two = temp;
+  }
+
+  return one;
+}
+
+console.log(climbStairs(3));