Distinct subsequences solution

Author: joshguha

115_distinct_subsequences.py

@@ -0,0 +1,19 @@
+class Solution(object):
+    def numDistinct(self, s, t):
+        """
+        :type s: str
+        :type t: str
+        :rtype: int
+        """
+        # https://discuss.leetcode.com/topic/51131/space-o-mn-and-o-n-python-solutions
+        dp = [[0 for j in xrange(0, len(t) + 1)] for i in xrange(0, len(s) + 1)]
+        for j in xrange(1, len(t) + 1):
+            dp[0][j] = 0
+        for i in xrange(1, len(s) + 1):
+            dp[i][0] = 1
+        dp[0][0] = 1
+        for i in xrange(1, len(s) + 1):
+            for j in xrange(1, len(t) + 1):
+                dp[i][j] = dp[i - 1][j] + dp[i - 1][j - 1] * (s[i - 1] == t[j - 1])
+
+        return dp[-1][-1]