1035. Uncrossed Lines.cpp

#MayChallenge
/*
Link: https://leetcode.com/problems/uncrossed-lines/

We write the integers of A and B (in the order they are given) on two separate horizontal lines.

Now, we may draw connecting lines: a straight line connecting two numbers A[i] and B[j] such that:

A[i] == B[j];
The line we draw does not intersect any other connecting (non-horizontal) line.
Note that a connecting lines cannot intersect even at the endpoints: each number can only belong to one connecting line.

Return the maximum number of connecting lines we can draw in this way.

 

Example 1:


Input: A = [1,4,2], B = [1,2,4]
Output: 2
Explanation: We can draw 2 uncrossed lines as in the diagram.
We cannot draw 3 uncrossed lines, because the line from A[1]=4 to B[2]=4 will intersect the line from A[2]=2 to B[1]=2.
Example 2:

Input: A = [2,5,1,2,5], B = [10,5,2,1,5,2]
Output: 3
Example 3:

Input: A = [1,3,7,1,7,5], B = [1,9,2,5,1]
Output: 2
 

Note:

1 <= A.length <= 500
1 <= B.length <= 500
1 <= A[i], B[i] <= 2000
*/


// Solution

class Solution {
public:
    int maxUncrossedLines(vector<int>& A, vector<int>& B) {
        int m = A.size(), n = B.size(), dp[m+1][n+1];
        memset(dp, 0, sizeof(dp));
        for (int i = 1; i <= m; ++i)
            for (int j = 1; j <= n; ++j)
                dp[i][j] = A[i - 1] == B[j - 1] ? dp[i - 1][j - 1] + 1 : max(dp[i][j - 1], dp[i - 1][j]);
        return dp[m][n];
    }
};