Added 2d-array DP solution

Author: shichao-an

distinct_subsequences/solution2.py

@@ -0,0 +1,14 @@
+class Solution:
+    # @return an integer
+    def numDistinct(self, S, T):
+        m = len(S)
+        n = len(T)
+        dp = [[0 for j in range(m + 1)] for i in range(n + 1)]
+        for j in range(m + 1):
+            dp[0][j] = 1
+        for i in range(1, n + 1):
+            for j in range(1, m + 1):
+                dp[i][j] = dp[i][j - 1]
+                if T[i - 1] == S[j - 1]:
+                    dp[i][j] += dp[i - 1][j - 1]
+        return dp[n][m]