Create uniquepaths.py

python/uniquepaths.py

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+#Number of unique paths to bottom right of an mxn grid
+class Solution:
+    def uniquePaths(self, m: int, n: int) -> int:
+
+        #Initialize 2D dp array
+        dp = [[1 for i in range(n)] for j in range(m)]
+
+
+        for i in range(1,m):
+            for j in range(1,n):
+
+                # As we can only move down or right,
+                # Number of paths to a cell is sum from
+                # upper cell and left cell
+                dp[i][j] = dp[i-1][j]+dp[i][j-1]
+
+        #Number of paths to last cell
+        return dp[-1][-1]