add 115

Author: luliyucoordinate

README.md

@@ -84,6 +84,7 @@ LeetCode
 |0111|[Minimum Depth of Binary Tree](https://leetcode.com/problems/minimum-depth-of-binary-tree/) | c | [c++](./src/0111-Minimum-Depth-of-Binary-Tree/0111.cpp) |[python](./src/0111-Minimum-Depth-of-Binary-Tree/0111.py)|||Easy|
 |0112|[Path Sum](https://leetcode.com/problems/path-sum/) | c | [c++](./src/0112-Path-Sum/0112.cpp) |[python](./src/0112-Path-Sum/0112.py)|||Easy|
 |0113|[Path Sum II](https://leetcode.com/problems/path-sum-ii/) | c | [c++](./src/0113-Path-Sum-II/0113.cpp) |[python](./src/0113-Path-Sum-II/0113.py)|||Medium|
+|0115|[Distinct Subsequences](https://leetcode.com/problems/distinct-subsequences/) | c | [c++](./src/0115-Distinct-Subsequences/0115.cpp) |[python](./src/0115-Distinct-Subsequences/0115.py)|||Hard|
 |0118|[Pascal's Triangle](https://leetcode.com/problems/pascals-triangle/) | c | [c++](./src/0118-Pascal's-Triangle/0118.cpp) |[python](./src/0118-Pascal's-Triangle/0118.py)|||Easy|
 |0119|[Pascal's Triangle II](https://leetcode.com/problems/pascals-triangle-ii/) | c | [c++](./src/0119-Pascal's-Triangle-II/0119.cpp) |[python](./src/0119-Pascal's-Triangle-II/0119.py)|||Easy|
 |0120|[Triangle](https://leetcode.com/problems/triangle/) | c | [c++](./src/0120-Triangle/0120.cpp) |[python](./src/0120-Triangle/0120.py)|||Medium|
@@ -197,4 +198,5 @@ LeetCode
 |0935|[Knight Dialer](https://leetcode.com/problems/knight-dialer/) | c | [c++](./src/0935-Knight-Dialer/0935.cpp) |[python](./src/0935-Knight-Dialer/0935.py)|||Medium|
 |0936|[Stamping The Sequence](https://leetcode.com/problems/stamping-the-sequence/) | c | [c++](./src/0936-Stamping-The-Sequence/0936.cpp) |[python](./src/0936-Stamping-The-Sequence/0936.py)|||Hard|
 |0937|[Reorder Log Files](https://leetcode.com/problems/reorder-log-files/) | c | [c++](./src/0937-Reorder-Log-Files/0937.cpp) |[python](./src/0937-Reorder-Log-Files/0937.py)|||Easy|
-|0938|[Range Sum of BST](https://leetcode.com/problems/range-sum-of-bst/) | c | [c++](./src/0938-Range-Sum-of-BST/0938.cpp) |[python](./src/0938-Range-Sum-of-BST/0938.py)|||Medium|
+|0938|[Range Sum of BST](https://leetcode.com/problems/range-sum-of-bst/) | c | [c++](./src/0938-Range-Sum-of-BST/0938.cpp) |[python](./src/0938-Range-Sum-of-BST/0938.py)|||Medium|
+|0939|[Minimum Area Rectangle](https://leetcode.com/problems/minimum-area-rectangle/) | c | [c++](./src/0939-Minimum-Area-Rectangle/0939.cpp) |[python](./src/0939-Minimum-Area-Rectangle/0939.py)|||Medium|

src/0115-Distinct-Subsequences/0115.cpp

@@ -0,0 +1,31 @@
+#include <iostream>
+#include <string>
+#include <vector>
+using namespace std;
+
+
+static int x = []() {std::ios::sync_with_stdio(false); cin.tie(0); return 0; }();
+class Solution 
+{
+public:
+    int numDistinct(string s, string t) 
+    {
+        vector<int> mem(t.size()+1, 0);
+        mem[0] = 1;
+        for (auto s_c : s)
+        {
+            for (int i = t.size() - 1; i >= 0; --i)
+            {
+                if (t[i] == s_c) mem[i+1] += mem[i];
+            }
+        }
+        return *mem.rbegin();
+    }
+};
+int main(int argc, char const *argv[])
+{
+    string s = "rabbbit";
+    string t = "rabbit";
+    cout << Solution().numDistinct(s, t);
+    return 0;
+}

src/0115-Distinct-Subsequences/0115.py

@@ -0,0 +1,21 @@
+class Solution:
+    def numDistinct(self, s, t):
+        """
+        :type s: str
+        :type t: str
+        :rtype: int
+        """
+        t_len = len(t)
+        mem = [0]*(t_len+1)
+        mem[0] = 1
+        for s_c in s:
+            for i in range(t_len-1, -1, -1):
+                if t[i] == s_c:
+                    mem[i+1] += mem[i]
+
+        return mem[-1]
+        
+if __name__ == "__main__":
+    s = "rabbbit"
+    t = "rabbit"
+    print(Solution().numDistinct(s, t))