@@ -28,19 +28,16 @@ def longest_common_subsequence(s1, s2):
 :param s2: string
 :return: int
 """
-m = len(s1)
-n = len(s2)
+m, n = len(s1), len(s2)
 
-dp = [[0] * (n + 1) for i in range(m + 1)]
+dp = [[0] * (n + 1)] * (m + 1)
 """
 dp[i][j] : contains length of LCS of s1[0..i-1] and s2[0..j-1]
 """
 
-for i in range(m + 1):
-for j in range(n + 1):
-if i == 0 or j == 0:
-dp[i][j] = 0
-elif s1[i - 1] == s2[j - 1]:
+for i in range(1, m + 1):
+for j in range(1, n + 1):
+if s1[i - 1] == s2[j - 1]:
 dp[i][j] = dp[i - 1][j - 1] + 1
 else:
 dp[i][j] = max(dp[i - 1][j], dp[i][j - 1])