LeetCode-in-All
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 <= 1000text1andtext2consist of only lowercase English characters.
Solution
object Solution {
def longestCommonSubsequence(text1: String, text2: String): Int = {
val n = text1.length
val m = text2.length
val dp = Array.ofDim[Int](n + 1, m + 1)
for (i <- 1 to n) {
for (j <- 1 to 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))
}
}
}
dp(n)(m)
}
}