原题链接在这里：https://leetcode.com/problems/maximum-length-of-repeated-subarray/

题目：

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

题解：

The subarray must be continuous. 

dp[i][j] denotes the maximum length of repeated subarray between A up to index i and B up to index j.

if(A[i] == B[j]) dp[i][j] = dp[i-1][j-1]+1.

if(A[i] != B[j]) d[i][j] = 0.

Time Complexity: O(m*n).

Space: O(m*n).

AC Java:

 1 class Solution {
 2     public int findLength(int[] A, int[] B) {
 3         if(A == null || A.length == 0 || B == null || B.length == 0){
 4             return 0;
 5         }
 6         
 7         int m = A.length;
 8         int n = B.length;
 9         int [][] dp = new int[m+1][n+1];
10         int res = 0;
11         for(int i = 1; i<=m; i++){
12             for(int j = 1; j<=n; j++){
13                 if(A[i-1] == B[j-1]){
14                     dp[i][j] = dp[i-1][j-1]+1;
15                     res = Math.max(res, dp[i][j]);
16                 }
17             }
18         }
19         
20         return res;
21     }
22 }

类似Longest Common Subsequence, Minimum ASCII Delete Sum for Two Strings, Delete Operation for Two Strings.