Added Python solution for 62. Unique Paths (Tahanima#118)

* Added Python solution for 62. UniquePaths

* Changes added to Python solution for 62. UniquePaths

Author: JoyKrishan

Algorithms/Medium/62_UniquePaths/Solution.py

@@ -0,0 +1,12 @@
+class Solution:
+    def uniquePaths(self, m: int, n: int) -> int:
+        bottom_row = [1] * n
+        
+        for column in range(m - 1):
+            new_row = [1] * n
+
+            for i in range(n - 2, -1, -1):
+                new_row[i] = new_row[i + 1] + bottom_row[i]
+            bottom_row = new_row
+        
+        return bottom_row[0]