from math import ceil
def sorting_value(nums, x = 0):
if sorted(nums) == nums: return x
if sorted(nums, reverse= True) == nums: return nums[0] + 1
x = []
for i in range(1,len(nums)):
if nums[i - 1] > nums[i]:
x += [ceil ((nums[i - 1] + nums[i]) / 2)]
x = max(x)
sorted_nums = [abs (num - x) for num in nums]
if sorted(sorted_nums) == sorted_nums: return x
return -1
if __name__ == "__main__":
for _ in range(int(input())):
input()
nums = [int(x) for x in input().split()]
value = sorting_value(nums)
print (value)#include <bits/stdc++.h>
using namespace std;
int main()
{
int t;
cin >> t;
for(int i = 0; i < t; i++)
{
int n;
cin >> n;
vector<int> a(n);
for(int j = 0; j < n; j++)
cin >> a[j];
int mn = 0, mx = int(1e9);
for(int j = 0; j + 1 < n; j++)
{
int x = a[j];
int y = a[j + 1];
int midL = (x + y) / 2;
int midR = (x + y + 1) / 2;
if(x < y)
mx = min(mx, midL);
if(x > y)
mn = max(mn, midR);
}
if(mn <= mx) cout << mn << endl;
else cout << -1 << endl;
}
}320A - Magic Numbers | 1658A - Marin and Photoshoot |
514A - Chewbaсca and Number | 382A - Ksenia and Pan Scales |
734B - Anton and Digits | 1080A - Petya and Origami |
1642D - Repetitions Decoding | 1440A - Buy the String |
1658F - Juju and Binary String | 478A - Initial Bet |
981A - Antipalindrome | 365A - Good Number |
1204B - Mislove Has Lost an Array | 1409D - Decrease the Sum of Digits |
1476E - Pattern Matching | 1107A - Digits Sequence Dividing |
1348A - Phoenix and Balance | 1343B - Balanced Array |
1186A - Vus the Cossack and a Contest | 1494A - ABC String |
1606A - AB Balance | 1658C - Shinju and the Lost Permutation |
1547C - Pair Programming | 550A - Two Substrings |
797B - Odd sum | 1093A - Dice Rolling |
1360B - Honest Coach | 1399C - Boats Competition |
1609C - Complex Market Analysis | 1657E - Star MST |