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1143. Longest Common Subsequence.py
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1143. Longest Common Subsequence.py
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class Solution:
def longestCommonSubsequence(self, text1: str, text2: str) -> int:
# Get the lengths of both input strings
len_text1, len_text2 = len(text1), len(text2)
# Initialize a 2D array (list of lists) with zeros for dynamic programming
# The array has (len_text1 + 1) rows and (len_text2 + 1) columns
dp_matrix = [[0] * (len_text2 + 1) for _ in range(len_text1 + 1)]
# Loop through each character index of text1 and text2
for i in range(1, len_text1 + 1):
for j in range(1, len_text2 + 1):
# If the characters match, take the diagonal value and add 1
if text1[i - 1] == text2[j - 1]:
dp_matrix[i][j] = dp_matrix[i - 1][j - 1] + 1
else:
# If the characters do not match, take the maximum of the value from the left and above
dp_matrix[i][j] = max(dp_matrix[i - 1][j], dp_matrix[i][j - 1])
# The bottom-right value in the matrix contains the length of the longest common subsequence
return dp_matrix[len_text1][len_text2]