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
impl Solution {
pub fn longest_common_subsequence(text1: String, text2: String) -> i32 {
let n = text1.len();
let m = text2.len();
// Create a 2D dp array initialized to 0
let mut dp = vec![vec![0; m + 1]; n + 1];
// Convert the strings to a vector of chars for easier access
let chars1: Vec<char> = text1.chars().collect();
let chars2: Vec<char> = text2.chars().collect();
// Fill the dp array
for i in 1..=n {
for j in 1..=m {
if chars1[i - 1] == chars2[j - 1] {
dp[i][j] = dp[i - 1][j - 1] + 1;
} else {
dp[i][j] = dp[i - 1][j].max(dp[i][j - 1]);
}
}
}
dp[n][m]
}
}