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
function longestCommonSubsequence(text1: string, text2: string): number {
const n: number = text1.length
const m: number = text2.length
const dp: number[][] = new Array(n + 1).fill(null).map(() => new Array(m + 1).fill(0))
for (let i = 1; i <= n; i++) {
for (let j = 1; j <= m; j++) {
if (text1.charAt(i - 1) === text2.charAt(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]
}
export { longestCommonSubsequence }