-- submissions_per_day
with hacker_submissions as
(select hacker_id, submission_date,count(submission_id) submission_cnt
    from submissions group by hacker_id, submission_date),

-- rank hackers on submission_cnt
ranked_hackers as (select hs.submission_date,hs.hacker_id, submission_cnt,
    row_number() over (partition by hs.submission_date order by submission_cnt desc, hs.hacker_id asc) rnk
    from hacker_submissions hs),

-- eligible hackers
cte as (select hacker_id, submission_date,
count(submission_cnt) over (partition by hacker_id order by submission_date) date_before_submissions
from hacker_submissions),
eligible_hackers as (select hacker_id,submission_date from cte where
                    day(submission_date) = date_before_submissions),

-- unique eligible hackers count
unique_hackers as (select submission_date, count(hacker_id) unique_cnt
                   from eligible_hackers group by submission_date)

--combine tables
select rh.submission_date,uh.unique_cnt,rh.hacker_id,h.name from
ranked_hackers rh
inner join unique_hackers uh on uh.submission_date=rh.submission_date
inner join hackers h on h.hacker_id = rh.hacker_id
where rh.rnk=1
order by rh.submission_date

SELECT A.submission_date, A.unique_hackers, B.top_hacker_id, B.name
FROM

(SELECT submission_date AS submission_date, SUM(unique_hackers) AS unique_hackers FROM
    (SELECT s1.submission_date AS submission_date, COUNT(DISTINCT s2.hacker_id) AS unique_hackers
    FROM Submissions s1 JOIN Submissions s2
    ON s2.submission_date <= s1.submission_date
    GROUP BY s1.submission_date, s2.hacker_id
    HAVING COUNT(DISTINCT s2.submission_date) = DAY(s1.submission_date)
    ORDER BY s1.submission_date) uk
GROUP BY submission_date 
ORDER BY submission_date) A

JOIN

(SELECT t.submission_date AS submission_date, t.top_hacker_id AS top_hacker_id, h.name AS name
FROM
(SELECT s3.submission_date AS submission_date, 
    (SELECT hacker_id FROM Submissions s4
     WHERE s4.submission_date = s3.submission_date
     GROUP BY s4.hacker_id
     ORDER BY COUNT(s4.submission_id) DESC, s4.hacker_id 
     LIMIT 1) AS top_hacker_id
 FROM Submissions s3
 GROUP BY s3.submission_date) t 
JOIN Hackers h
ON t.top_hacker_id = h.hacker_id
ORDER BY t.submission_date) B

ON A.submission_date = B.submission_date
ORDER BY A.submission_date;

Check this Out Guys  

SELECT A.SUBMISSION_DATE , A.CNT , B.CL2 , B.NAME FROM 
(
    SELECT TB8.SUBMISSION_DATE , COUNT(TB8.HACKER_ID) AS CNT FROM 
(
    SELECT TB6.SUBMISSION_DATE , TB6.HACKER_ID FROM 
    (
        SELECT SUBMISSION_DATE , HACKER_ID 
        FROM SUBMISSIONS GROUP BY SUBMISSION_DATE , HACKER_ID
    )AS TB6
    WHERE TB6.HACKER_ID IN 
    (
        SELECT TB7.HACKER_ID FROM 
        (
            SELECT SUBMISSION_DATE , HACKER_ID
            FROM SUBMISSIONS GROUP BY SUBMISSION_DATE , HACKER_ID
        ) AS TB7
        WHERE TB7.SUBMISSION_DATE <= TB6.SUBMISSION_DATE
        GROUP BY TB7.HACKER_ID 
        HAVING COUNT(TB7.HACKER_ID) = DATEDIFF(TB6.SUBMISSION_DATE,'2016-03-01')+1  
    )
) AS TB8
GROUP BY TB8.SUBMISSION_DATE
) AS A 
JOIN 
(
SELECT A.SUBMISSION_DATE , A.CL2 , B.NAME FROM 
(
    SELECT TB2.SUBMISSION_DATE ,
    (
        SELECT HACKER_ID
        FROM SUBMISSIONS 
        WHERE SUBMISSION_DATE = TB2.SUBMISSION_DATE
        GROUP BY SUBMISSION_DATE, HACKER_ID
        ORDER BY COUNT(HACKER_ID) DESC , HACKER_ID ASC LIMIT 1 
    ) AS CL2
    FROM 
    (SELECT DISTINCT (SUBMISSION_DATE) AS SUBMISSION_DATE FROM SUBMISSIONS)
    AS TB2
) AS A
LEFT JOIN 
HACKERS AS B 
ON A.CL2 = B.HACKER_ID
) AS B 
ON A.SUBMISSION_DATE = B.SUBMISSION_DATE 
ORDER BY A.SUBMISSION_DATE