def main():
    n = int(input())
    A = list(map(int, input().split()))
    if n == 1:
        if A[0] == 0:
            return 1
        else:
            return A[0]
    A.sort()
    A = A[::-1]
    l = 0
    r = n+2
    p = 100
    def cal(m):
        if m < 0: return 0
        c = 0
        t = m-1
        s = 1
        k = 1
        for a in A:
            if a > t:
                c += 1
            elif a == t:
                k -= 1
                if not k:
                    t -= 1
                    k = s
            else:
                while a < t:
                    s += k
                    k = s
                    t -= 1
                k -= 1
                if not k:
                    t -= 1
                    k = s
            if t <= -1:
                l = m
                return 1
        while t:
            s += k
            k = s
            t -= 1
        if s <= c:
            return 1
        else:
            return 0
    while r-l > 1:
        m = (l+r) >> 1
        if cal(m):
            l = m
        else:
            r = m
    ans = 0
    for ni in range(r-10, r+10):
        if cal(ni):
            ans = ni
    return ans
for _ in range(int(input())):
    print(main())