leetcode 718. Maximum Length of Repeated Subarray

Question

Given two integer arrays A and B, return the maximum length of an subarray that appears in both arrays. https://leetcode.com/problems/maximum-length-of-repeated-subarray/

Code

class Solution {
public:
    int findLength(vector<int>& A, vector<int>& B) {
        // dp[i][j] will be the maximum length of subarray which ends with A[i] and B[j]
        // ex) 
// A: [1,2,3,2,1]
// B: [3,2,1,4,7]
        // dp [4][1] =  2;
        // if A[i+1] == B[j+1] dp[i+1][j+1] = dp[i][j] + 1  
        // else dp[i+1][j+1] = 0;
        // Time O(mn);
        // Space O(mn);
        vector<vector<int> > dp = vector<vector<int> >(A.size() + 1, vector<int>(B.size()  + 1, 0));

        int ans = 0;
        for(int i = 0; i < A.size(); i++) {
            for(int j = 0; j < B.size(); j++) {
                if(A[i] == B[j]) {
                    if(i - 1 < 0 || j - 1 < 0 ) {
                        dp[i][j] = 1;
                    } else {
                        dp[i][j] = dp[i-1][j-1]  + 1;
                        
                    }
                } else {
                    dp[i][j] = 0;
                }
                ans = max(dp[i][j], ans);
            }
        }

        return ans;
        
        
    }
};