Codeforce:b. difference array [optimization of prefix 0]

analysis

If you don't need to sort It is a simple combinatorial number problem
Now is the simulation of violence
However, Prefix 0 Many and useless
So we maintain a wave of prefixes independently 0
You don't have to do it when sorting

ac code

import sys
input = sys.stdin.readline




for _ in range(int(input())):
    n = int(input())
    a = list(map(int, input().split()))
    # we use the 0's at the beginning to optimize
    x = []

    while len(a) > 1:
        tmp = []
        for i in range(1, len(a)):
            if a[i] - a[i - 1] == 0:
                x.append(0)
            else:
                tmp.append(a[i] - a[i - 1])
        b = []
        if x:
            b = [0]
            x.pop()
        a = b + sorted(tmp)

    print(*a)

summary

The skill of doing questions is to look at examples
Found that there are many prefixes 0
Just think of ignoring them
About their maintenance, we need to add an extra list Let's see their number
Pop up one at a time , If there is any more, it should be included