leetcode.com 115. Distinct Subsequences

문제 링크: https://leetcode.com/problems/distinct-subsequences/description/

Author: skysign

leetcode.com 115. Distinct Subsequences/main.py

@@ -0,0 +1,27 @@
+from typing import List
+
+
+class Solution:
+    def numDistinct(self, s: str, t: str) -> int:
+        s = ' ' + s
+        t = ' ' + t
+        l_s = len(s)
+        l_t = len(t)
+        dp: List[List[int]] = [[[-1, 0] for _ in range(len(s))] for _ in range(len(t))]
+        dp[0][0][0] = 0  # s의 0~c인덱스까지, t의 0~r인덱스까지 비교하여, match된 distinct subsequence 임을 뜻함
+        dp[0][0][1] = 1  # s의 0~c인덱스까지, t의 0~r인덱스까지 비교하여, match된 distinct subsequence 의 개수
+
+        answer = 0
+
+        for r in range(1, l_t):
+            for c in range(r, l_s - (l_t - r - 1)):
+                if t[r] == s[c]:
+                    for b in range(r - 1, c):
+                        if dp[r - 1][b][0] == r - 1:
+                            dp[r][c][0] = r
+                            dp[r][c][1] += dp[r - 1][b][1]
+
+                            if dp[r][c][0] == l_t - 1:
+                                answer += dp[r - 1][b][1]
+
+        return answer

leetcode.com 115. Distinct Subsequences/test_main.py

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+from unittest import TestCase
+from main import Solution
+
+
+class TestSolution(TestCase):
+    def test1_num_distinct(self):
+        sol = Solution()
+        self.assertEqual(3, sol.numDistinct(s="rabbbit", t="rabbit"))
+
+    def test2_num_distinct(self):
+        sol = Solution()
+        self.assertEqual(5, sol.numDistinct(s="babgbag", t="bag"))