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
/**
* @param {string} text1
* @param {string} text2
* @return {number}
*/
var longestCommonSubsequence = function(text1, text2) {
const rows = text1.length
const columns = text2.length
let prevRow = new Array(text2.length + 1).fill(0)
for (let i = rows - 1; i >= 0; i--) {
const curRow = new Array(text2.length + 1).fill(0)
for (let j = columns - 1; j >= 0; j--) {
if (text1[i] == text2[j]) {
curRow[j] = 1 + prevRow[j + 1]
} else {
curRow[j] = Math.max(prevRow[j], curRow[j + 1])
}
}
prevRow = curRow
}
return prevRow[0]
};
export { longestCommonSubsequence }