for _ in range(int(input())):
input()
a = list(map(int, input().split()))
previous = a[-1]
it = 0
for el in reversed(a[:-1]):
if el > previous:
it += el - previous
previous = el
print(it)#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define IOS ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define endl "\n"
void solve(){
ll n;
cin>>n;
vector<ll> v(n);
for(ll i=0;i<n;i++) cin>>v[i];
ll ans =0;
for(ll i=1;i<n;i++){
ans += max((v[i-1]-v[i]),1ll*0);
}
cout<<ans<<endl;
}
int main()
{
IOS
//precomp();
ll t;
cin>>t;
while(t--) solve();
return 0;
}561. Array Partition I | 1374. Generate a String With Characters That Have Odd Counts |
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1323. Maximum 69 Number | 832. Flipping an Image |
1295. Find Numbers with Even Number of Digits | 1704. Determine if String Halves Are Alike |
1732. Find the Highest Altitude | 709. To Lower Case |
1688. Count of Matches in Tournament | 1684. Count the Number of Consistent Strings |
1588. Sum of All Odd Length Subarrays | 1662. Check If Two String Arrays are Equivalent |
1832. Check if the Sentence Is Pangram | 1678. Goal Parser Interpretation |
1389. Create Target Array in the Given Order | 1313. Decompress Run-Length Encoded List |
1281. Subtract the Product and Sum of Digits of an Integer | 1342. Number of Steps to Reduce a Number to Zero |
1528. Shuffle String | 1365. How Many Numbers Are Smaller Than the Current Number |
771. Jewels and Stones | 1512. Number of Good Pairs |
672. Richest Customer Wealth | 1470. Shuffle the Array |
1431. Kids With the Greatest Number of Candies | 1480. Running Sum of 1d Array |
682. Baseball Game | 496. Next Greater Element I |