Create Longest Common Subsequence - Leetcode 1143.py

Author: gahogg

Longest Common Subsequence - Leetcode 1143.py

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+class Solution:
+    def longestCommonSubsequence(self, text1: str, text2: str) -> int:
+        # Top Down DP (Memoization)
+        # Time: O(m*n)
+        # Space: O(m*n)
+
+        m, n = len(text1), len(text2)
+
+        @cache
+        def longest(i, j):
+            if i == m or j == n:
+                return 0
+            elif text1[i] == text2[j]:
+                return 1 + longest(i+1, j+1)
+            else:
+                return max(longest(i, j+1), longest(i+1, j))
+        
+        return longest(0, 0)
+      
+class Solution:
+    def longestCommonSubsequence(self, text1: str, text2: str) -> int:
+	      # Bottom Up DP (Tabulation)
+	      # Time: O(m*n)
+        # Space: O(m*n)
+
+        m, n = len(text1), len(text2)
+        dp = [[0] * (n+1) for _ in range(m + 1)]
+
+        for i in range(1, m+1):
+            for j in range(1, n+1):
+                if text1[i-1] == text2[j-1]:
+                    dp[i][j] = dp[i-1][j-1] + 1
+                else:
+                    dp[i][j] = max(dp[i-1][j], dp[i][j-1])
+        
+        return dp[m][n]
+        
+
+