import java.util.*;
public class Solution {
/**
*
* @param arr int整型一维数组 the array
* @return int整型
*/
public int maxLength (int[] arr) {
// write code here
if(arr.length == 0){
return 0;
}
HashMap<Integer,Integer> hm = new HashMap<>();
int max = 0;
for(int i = 0 ,j=0;i < arr.length; i++){
if(hm.containsKey(arr[i])){
j = Math.max(j,hm.get(arr[i])+1);
}
hm.put(arr[i],i);
max = Math.max(max,i-j+1);
}
return max;
}
}