i was doing leetcode problem #553 (just studying) and i was stuck with time limit exceptions. i gave my code to the chatgpt to tell me how can i optimise it and it gave me this code:

public bool CheckSubArraySumV2(int[] nums, int k)
{
    if(nums.Length < 2) return false;

    Dictionary<int, int> sums = new()
    {
        [0] = -1
    };

    int sum = 0;

    for(int i = 0; i < nums.Length; i++)
    {
        sum += nums[i];
        int remain = sum % k;
        if(sums.ContainsKey(remain))
        {
            if(i - sums[remain] > 1)
            {
                return true;
            }
        }
        else{
            sums[remain] = i;
        }
    }

    return false;
}

and after i understood this method i copied it all except this nested if statement:

if (sums.ContainsKey(remain))
{
    if (i - sums[remain] > 1)
    {
        return true;
    }
}

i changed it to this:

if(sums.ContainsKey(remain) && i - sums[remain] > 1)
{
    return true;
}

but for some reason in testcase with nums = [5,0,0,0] and k = 3 ive got wrong answer (false instead of true).
after a several attempts i decided to replace && back with nested if statement and that was working fine for some reason.

so my question is, whats the difference between “&&” condition checking and nested if statement? isnt it working by short circuit?