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;
}767A - Snacktower | 1365A - Matrix Game |
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