718. Maximum Length of Repeated Subarray

Given two integer arrays A and B, return the maximum length of an subarray that appears in both arrays.

Example 1:

Input:
A: [1,2,3,2,1]
B: [3,2,1,4,7]
Output: 3
Explanation: 
The repeated subarray with maximum length is [3, 2, 1].

Note:

1. 1 <= len(A), len(B) <= 1000
2. 0 <= A[i], B[i] < 100

class Solution {
public:
    int findLength(vector<int>& A, vector<int>& B) {
        int m = A.size();
        int n = B.size();
        if(!m || !n ) return 0;
        int dp[m+1][n+1] = {};
        int mx = 0;
        for(int i=1; i<=m; i++)
        {
            for(int j=1; j<=n; j++)
            {
                if(A[i-1]==B[j-1]) 
                {
                     
                      dp[i][j] = dp[i-1][j-1] + 1;
                     
                }
                mx = max(mx, dp[i][j]);
            }
        }
        return mx;
    }
};

class Solution {
public:
    int findLength(vector<int>& a, vector<int>& b) {
        int m = a.size(), n = b.size();
        if (!m || !n) return 0;
        vector<int> dp(n + 1);
        int res = 0;
        for (int i = m - 1; i >= 0; i--) {
            for (int j = 0; j < n; j++) {
                res = max(res, dp[j] = a[i] == b[j] ? 1 + dp[j + 1] : 0);
            }
        }
        return res;
    }
};