Create 115-Distinct-Subsequences.py

Author: neetcode-gh

115-Distinct-Subsequences.py

@@ -0,0 +1,16 @@
+class Solution:
+    def numDistinct(self, s: str, t: str) -> int:
+        cache = {}
+        
+        for i in range(len(s) + 1):
+            cache[(i, len(t))] = 1
+        for j in range(len(t)):
+            cache[(len(s), j)] = 0
+        
+        for i in range(len(s) - 1, -1, -1):
+            for j in range(len(t) - 1, -1, -1):
+                if s[i] == t[j]:
+                    cache[(i, j)] = cache[(i+1,j+1)] + cache[(i+1,j)]
+                else:
+                    cache[(i,j)] = cache[(i+1,j)]
+        return cache[(0,0)]