feat: complete lc-62

apps/docs/content/(05-decision-space)/multi-d-grid-dp/62-unique-paths.mdx

@@ -0,0 +1,40 @@
+---
+title: '62. Unique Paths'
+description: There is a robot on an m x n grid. The robot is initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-right corner (i.e., grid[m - 1][n - 1]). The robot can only move either down or right at any point in time
+icon: dot
+topics:
+  - { name: "Math", slug: "math" }
+  - { name: "Dynamic Programming", slug: "dynamic-programming" }
+  - { name: "Combinatorics", slug: "combinatorics" }
+sidebar:
+  label: 'Unique Paths'
+  badge: 'Medium'
+---
+
+### Example 1:
+- Input: `m = 3, n = 7`
+- Output: `28`
+
+### Example 2:
+- Input: `m = 3, n = 2`
+- Output: `3`
+- Explanation: From the top-left corner, there are a total of `3` ways to reach the bottom-right corner: `1`. Right -> Down -> Down `2`. Down -> Down -> Right `3`. Down -> Right -> Down
+
+### Constraints:
+
+- `1 <= m, n <= 100`
+
+## Solution
+
+```py
+class Solution:
+    def uniquePaths(self, m: int, n: int) -> int:
+        row = [1] * n
+
+        for i in range(m - 1):
+            newRow = [1] * n
+            for j in range(n - 2, -1, -1):
+                newRow[j] = newRow[j + 1] + row[j]
+            row = newRow
+        return row[0]
+```

apps/docs/content/(05-decision-space)/multi-d-grid-dp/meta.ts

@@ -0,0 +1,3 @@
+import { defineMeta } from "blume";
+
+export default defineMeta({ title: "Multi-D / Grid DP", order: 22, icon: "table", display: "group" });

apps/docs/content/guides/combinatorics.mdx

@@ -0,0 +1,8 @@
+---
+title: "Combinatorics"
+list: "https://leetcode.com/problem-list/combinatorics/"
+---
+
+:::note
+This guide has not been written yet. The LeetCode list above has every problem tagged Combinatorics.
+:::

apps/docs/redirects.ts

@@ -16,6 +16,7 @@ export default [
   { from: "/48", to: "/matrix-index-math/rotate-image" },
   { from: "/49", to: "/hash-table/group-anagrams" },
   { from: "/54", to: "/matrix-index-math/spiral-matrix" },
+  { from: "/62", to: "/multi-d-grid-dp/unique-paths" },
   { from: "/70", to: "/1d-dynamic-programming/climbing-stairs" },
   { from: "/73", to: "/matrix-index-math/set-matrix-zeroes" },
   { from: "/74", to: "/binary-search/search-a-2d-matrix" },

work/1/Medium/Math/62.unique-paths.py

@@ -0,0 +1,53 @@
+"""
+62. Unique Paths
+Difficulty: Medium
+https://leetcode.com/problems/unique-paths/
+
+──────────────────────────────────────────────────
+
+There is a robot on an m x n grid. The robot is initially located at
+the top-left corner (i.e., grid[0][0]). The robot tries to move to the
+bottom-right corner (i.e., grid[m - 1][n - 1]). The robot can only
+move either down or right at any point in time.
+
+Given the two integers m and n, return the number of possible unique
+paths that the robot can take to reach the bottom-right corner.
+
+The test cases are generated so that the answer will be less than or
+equal to 2 * 10^9.
+
+
+
+Example 1:
+
+Input: m = 3, n = 7
+Output: 28
+
+Example 2:
+
+Input: m = 3, n = 2
+Output: 3
+Explanation: From the top-left corner, there are a total of 3 ways to
+reach the bottom-right corner:
+1. Right -> Down -> Down
+2. Down -> Down -> Right
+3. Down -> Right -> Down
+
+
+
+Constraints:
+
+        • 1 <= m, n <= 100
+"""
+
+
+class Solution:
+    def uniquePaths(self, m: int, n: int) -> int:
+        row = [1] * n
+
+        for i in range(m - 1):
+            newRow = [1] * n
+            for j in range(n - 2, -1, -1):
+                newRow[j] = newRow[j + 1] + row[j]
+            row = newRow
+        return row[0]