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]
+```