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64 lines
1.7 KiB
Python
64 lines
1.7 KiB
Python
"""
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1143. Longest Common Subsequence
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Difficulty: Medium
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https://leetcode.com/problems/longest-common-subsequence/
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──────────────────────────────────────────────────
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Given two strings text1 and text2, return the length of their longest
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common subsequence. If there is no common subsequence, return 0.
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A subsequence of a string is a new string generated from the original
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string with some characters (can be none) deleted without changing the
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relative order of the remaining characters.
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• For example, "ace" is a subsequence of "abcde".
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A common subsequence of two strings is a subsequence that is common
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to both strings.
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Example 1:
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Input: text1 = "abcde", text2 = "ace"
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Output: 3
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Explanation: The longest common subsequence is "ace" and its length
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is 3.
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Example 2:
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Input: text1 = "abc", text2 = "abc"
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Output: 3
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Explanation: The longest common subsequence is "abc" and its length
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is 3.
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Example 3:
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Input: text1 = "abc", text2 = "def"
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Output: 0
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Explanation: There is no such common subsequence, so the result is 0.
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Constraints:
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• 1 <= text1.length, text2.length <= 1000
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• text1 and text2 consist of only lowercase English characters.
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"""
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class Solution:
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def longestCommonSubsequence(self, text1: str, text2: str) -> int:
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dp = [[0 for j in range(len(text2) + 1)] for i in range(len(text1) + 1)]
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for i in range(len(text1) - 1, -1, -1):
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for j in range(len(text2) - 1, -1, -1):
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if text1[i] == text2[j]:
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dp[i][j] = 1 + dp[i + 1][j + 1]
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else:
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dp[i][j] = max(dp[i][j + 1], dp[i + 1][j])
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return dp[0][0]
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