LeetCode in Kotlin

1143. Longest Common Subsequence

Medium

Given two strings text1 and text2, return the length of their longest common subsequence. If there is no common subsequence, return 0.

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.

• For example, "ace" is a subsequence of "abcde".

A common subsequence of two strings is a subsequence that is common to both strings.

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, text2.length <= 1000
• text1 and text2 consist of only lowercase English characters.

Solution

class Solution {
    fun longestCommonSubsequence(text1: String, text2: String): Int {
        val n = text1.length
        val m = text2.length
        val dp = Array(n + 1) { IntArray(m + 1) }
        for (i in 1..n) {
            for (j in 1..m) {
                if (text1[i - 1] == text2[j - 1]) {
                    dp[i][j] = dp[i - 1][j - 1] + 1
                } else {
                    dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1])
                }
            }
        }
        return dp[n][m]
    }
}

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