Hey, I know the contest was postponed, but I was trying to solve this question:

Question:

Consider the integer sequence A[], where the elements are first N natural numbers in order.

You are now given two integers, L and S. Determine whether there exists a subarray with length L and sum S after removing at most one element from A.

A subarray of an array is a non-empty sequence obtained by removing zero or more elements from the front of the array, and zero or more elements from the back of the array.
1 <= N <= 10^9
1 <= L <= N - 1

I came up with something like this:

def solve(n, l, s):
    lo = 1
    hi = n

    def helper(i):
        one = i * (i+1) >> 1
        two = 0
        if i - l > 0:
            two = (i-l)*(i-l+1) >> 1
        return one - two
    for _ in range(100):
        mid = ((hi - lo) >> 1) + lo
        val = helper(mid)
        if abs(s - val) < 2:
            if lo == 1:
                if s - val >= 0:
                    return "YES"
            elif mid == n:
                if s - val <= 0:
                    return "YES"
            else:
                return "YES"
        if s > val:
            lo = mid + 1
        elif s < val:
            hi = mid - 1
    return "NO"


for _ in range(int(input())):
    n, l, s = map(int, input().split())

    print(solve(n, l, s))

Test Cases with the answers:

3
5 3 11 # YES
5 3 5 # NO
5 3 6 # YES

My code seems to pass the initial test cases, but I'd like to know if this will work for all cases. Please let me know if this is correct.