从给定的未排序整数数组中查找最长连续元素序列的长度

Question

I am having some trouble trying to find the longest consecutive elements of a sequence, and this part is the one that sorts the array and adds the length of the consecutive elements in an ArrayList. Could someone tell me why this code is wrong?

public static int longest_sequence(int[] array)
{
    int length = 0;
    // ArrayList to hold all lengths
    ArrayList<Integer> consecutiveArray = new ArrayList<Integer>();
    
    Arrays.sort(array);
    
    for (int i = 0; i < array.length - 1; i++)
    {
        if (array[i] + 1 == array[i + 1])
        {
            length++;
        }
        else
        {
            consecutiveArray.add(length);
            length = 0;
        }
    }

    Collections.sort(consecutiveArray);
    
    return consecutiveArray.get(consecutiveArray.size() - 1);
}

Answer 1

public static int longest_sequence(int[] array) {
    if (array.length == 0)
        return 0;

    int length = 1;
    int ans = 1;
    
    Arrays.sort(array);
    
    for (int i = 0; i < array.length - 1; i++)
    {
        if(array[i] == array[i+1]) {
            continue;
        }
        else if (array[i] + 1 == array[i + 1])
        {
            length++;
        }
        else
        {
            length = 1;
        }
        
        ans = Math.max(ans,length);
    }

    
    return ans;
}

Ok, assuming longest consecutive sequence isnt has to be ordered, you can do few things:

1. Length can always be one because longest consecutive sequence would always contain a single number, unless the input array is empty.
2. You need to skip equal consecutive numbers, which the first if does by continuing the iteration.
3. You don't need the consecutive_array, a single variable would be sufficient to hold the length of longest consecutive sequence, which the "ans" variable does.