1143. Longest Common Subsequence

Given two strings text1 and text2, return the length of their longest common subsequence.

A subsequence of a string is a new string generated from the original string with some characters(can be none) deleted without changing the relative order of the remaining characters. (eg, "ace" is a subsequence of "abcde" while "aec" is not). A common subsequence of two strings is a subsequence that is common to both strings.

If there is no common subsequence, return 0.

Example 1:

Input: text1 = "abcde", text2 = "ace"
Output: 3
Explanation: The longest common subsequence is "ace" and its length is 3.

Example 2:

Input: text1 = "abc", text2 = "abc"
Output: 3
Explanation: The longest common subsequence is "abc" and its length is 3.

Example 3:

Input: text1 = "abc", text2 = "def"
Output: 0
Explanation: There is no such common subsequence, so the result is 0.

Constraints:

• 1 <= text1.length <= 1000
• 1 <= text2.length <= 1000
• The input strings consist of lowercase English characters only.

# @lc code=start
using LeetCode

function longest_common_subsequence(itr1, itr2)::Int32
    m, n = length(itr1) + 1, length(itr2) + 1
    dp = fill(0, m, n)

    for i in 2:m, j in 2:n
        dp[i, j] = (itr1[i - 1] == itr2[j - 1]) ? (dp[i - 1, j - 1] + 1) : max(dp[i - 1, j], dp[i, j - 1])
    end

    return dp[m, n]
end
# @lc code=end

longest_common_subsequence (generic function with 1 method)

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