chore(Python): longest common subsequence (#322)

algorithms/Python/README.md

@@ -36,3 +36,4 @@
 3. [Word Count](strings/word_count.py)
 4. [Remove Duplicates from a String](strings/remove_duplicates_from_a_string.py)
 5. [First Non Repeating Character](strings/first_non_repeating_character.py)
+6. [Longest Common Subsequence](strings/longest_common_subsequence.py)

algorithms/Python/strings/longest_common_subsequence.py

@@ -0,0 +1,20 @@
+class Solution:
+    def longest_common_subsequence(self, text1: str, text2: str) -> int:
+        n,m = len(text1),len(text2)
+        
+        grid=[[0] * (m+1) for z in range(n+1)]
+        
+        for i in range(n):
+            for j in range(m):
+                
+                if text1[i]==text2[j]:
+                    grid[i+1][j+1]=grid[i][j] +1
+                    
+                else:
+                    grid[i+1][j+1]=max(grid[i][j+1], grid[i+1][j])
+                    
+        return grid[-1][-1]
+    
+if __name__=='__main__':
+    instance = Solution()
+    print(instance.longest_common_subsequence("abcdefg","aceg"))