Merge pull request #5 from GolubevDS/climbing-stairs

Climbing Stairs

Author: GolubevDS

README.MD

@@ -1,10 +1,7 @@
 # LEETCODE PATTERNS
 
----
-
 Solutions to problems from the [LeetCode Patterns](https://seanprashad.com/leetcode-patterns/) website
 
----
 ## Problems
 
 | Title                                                                                                                    | Solution                                                                                                      | Difficulty |
@@ -13,3 +10,4 @@ Solutions to problems from the [LeetCode Patterns](https://seanprashad.com/leetc
 | [268. Missing Number](https://leetcode.com/problems/missing-number/)                                                     | [Solution](https://github.com/GolubevDS/LeetCodePatterns/tree/main/solutions/missingNumber/index.js)          | Easy       |
 | [448. Find All Numbers Disappeared in an Array](https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/) | [Solution](https://github.com/GolubevDS/LeetCodePatterns/blob/main/solutions/findDisappearedNumbers/index.js) | Easy       |
 | [136. Single Number](https://leetcode.com/problems/single-number/)                                                       | [Solution](https://github.com/GolubevDS/LeetCodePatterns/blob/main/solutions/singleNumber/index.js)           | Easy       |
+| [70. Climbing Stairs](https://leetcode.com/problems/climbing-stairs/)                                                    | [Solution](https://github.com/GolubevDS/LeetCodePatterns/blob/main/solutions/climbStairs/index.js)            | Easy       |

solutions/climbStairs/README.MD

@@ -0,0 +1,9 @@
+## [70. Climbing Stairs](https://leetcode.com/problems/climbing-stairs/)
+
+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?
+
+#### Constraints:
+
+`1 <= n <= 45`

solutions/climbStairs/index.js

@@ -0,0 +1,19 @@
+const cache = [];
+
+/**
+ * @param {number} n
+ * @return {number}
+ */
+function climbStairs(n) {
+	if (n <= 3) {
+		return n;
+	}
+
+	if (!cache[n]) {
+		cache[n] = climbStairs(n - 2) + climbStairs(n - 1);
+	}
+
+	return cache[n];
+}
+
+module.exports = climbStairs;

solutions/climbStairs/index.spec.js

@@ -0,0 +1,21 @@
+const climbStairs = require('./index');
+
+describe('Climbing Stairs', () => {
+	it('1. Input: n = 1', () => {
+		const result = climbStairs(1);
+		const expected = 1;
+		expect(result).toStrictEqual(expected);
+	});
+
+	it('2. Input: n = 4', () => {
+		const result = climbStairs(4);
+		const expected = 5;
+		expect(result).toStrictEqual(expected);
+	});
+
+	it('3. Input: n = 45', () => {
+		const result = climbStairs(45);
+		const expected = 1836311903;
+		expect(result).toStrictEqual(expected);
+	});
+});

solutions/containsDuplicate/README.MD

@@ -1,5 +1,3 @@
-### [217. Contains Duplicate](https://leetcode.com/problems/contains-duplicate/)
-
----
+## [217. Contains Duplicate](https://leetcode.com/problems/contains-duplicate/)
 
 Given an integer array `nums`, return `true` if any value appears at least twice in the array, and return `false` if every element is distinct.

solutions/findDisappearedNumbers/README.MD

@@ -1,5 +1,3 @@
-### [448. Find All Numbers Disappeared in an Array](https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/)
-
----
+## [448. Find All Numbers Disappeared in an Array](https://leetcode.com/problems/find-all-numbers-disappeared-in-an-array/)
 
 Given an array `nums` of `n` integers where `nums[i]` is in the range `[1, n]`, return an array of all the integers in the range `[1, n]` that do not appear in `nums`.

solutions/missingNumber/README.MD

@@ -1,5 +1,3 @@
-### [268. Missing Number](https://leetcode.com/problems/missing-number/)
-
----
+## [268. Missing Number](https://leetcode.com/problems/missing-number/)
 
 Given an array `nums` containing `n` distinct numbers in the range `[0, n]`, return the only number in the range that is missing from the array.

solutions/singleNumber/README.MD

@@ -1,6 +1,4 @@
-### [136. Single Number](https://leetcode.com/problems/single-number/)
-
----
+## [136. Single Number](https://leetcode.com/problems/single-number/)
 
 Given a **non-empty** array of integers `nums`, every element appears twice except for one. Find that single one.