Problem: 2062C - Cirno and Operations
Language: C++23 (GCC 14-64, msys2)

Previous submission (verdict: Wrong answer on test 2):
    //#define MYDEBUG
    #ifndef oUwUo
    	#include <bits/stdc++.h>
     
    	using namespace std;
     
    	#define endl << "\n"
    	#define FOR(x, n) for (int x=0; x < n; x++)
    	#define ll long long
    	#define vi vector<int>
    	#define vpi vector<pair<int,int>>
    	#define vvi vector<vector<i>>
    	#define vll vector<ll>
    	#define vpll vector<pair<ll,ll>>
    	#define vvll vector<vector<ll,ll>>
    	#define mp make_pair
    	#define SMIN(x,y) x=min(x,y)
    	#define SMAX(x,y) x=max(x,y)
    	#define RNG(j,l,r) for(int j=l;j<r;j++)
    	#define REVRNG(j,l,r) for(int j=r-1;j>=l;j--)
     
    	#ifdef MYDEBUG
    	#define D(x) {cerr << #x << " = " << x endl;}
    	#define D2(x, y) {cerr << #x << " = " << x << "/t" << #y << " = " << y endl;}
    	#define DT(t,x) {cerr<<t<<"\t"<<#x<<" = "<<x endl;}
    	#define DIT(cont) {cerr<<"container: " <<#cont endl<<"\t"; for(auto x: cont){cerr<<x<<" ";} cerr endl;}
    	#define DITlmd(cont,lmd) {cerr<<"container: " <<#cont endl<<"\t"; for(auto x: cont){cerr<<lmd(x)<<" ";} cerr endl;}
    	#define DARR(arr,n) {cerr<<"array :"<<#arr endl <<"\t" ; FOR(i,n){cerr<<arr[i]<<" ";} cerr endl;}
    	#define DARRlmd(arr,n,lmd) {cerr<<"array :"<<#arr endl <<"\t" ; FOR(i,n){cerr<<lmd(arr[i])<<" ";} cerr endl;}
    	#define TT(tex) cerr<<tex endl;
    	#else
    	#define D(x)
    	#define D2(x, y)
    	#define DT(t,x)
    	#define DIT(cont)
    	#define DITlmd(cont,lmd)
    	#define DARR(arr,n)
    	#define DARRlmd(arr,n,lmd)
    	#define TT(tex)
    	#endif
    #endif

	
     
    void solve()
    {
    	// code
		int n; cin>>n;
		
		ll res=0;

		vll a(n),b(n-1);

		FOR(i,n) cin>>a[i];

		for(int el:a) res+=el;


		while(a.size()>1){
			int s=a.size();
			b.resize(s-1);
			ll value=0;
		

			FOR(i,s-1){
				b[i]=a[i]-a[i+1];
			}
			for(int el :b) value+=el;
			res=max(res,abs(value));

			swap(a,b);


		}

		cout<<res endl;

		


    
    	return;
    }
     
    int main()
    {
        cin.tie(0);
        cout.sync_with_stdio(0);
    	int _;
    	cin >> _;
    	for (int t = 1; t <= _; t++)
    	{
    		#ifdef MYDEBUG
    			cerr << "______________________ testcsase = " << t endl;
    		#endif
    		solve();
    	}
     
    	return 0;
    }





Submission (verdict: Accepted):
    //#define MYDEBUG
    #ifndef oUwUo
    	#include <bits/stdc++.h>
     
    	using namespace std;
     
    	#define endl << "\n"
    	#define FOR(x, n) for (int x=0; x < n; x++)
    	#define ll long long
    	#define vi vector<int>
    	#define vpi vector<pair<int,int>>
    	#define vvi vector<vector<i>>
    	#define vll vector<ll>
    	#define vpll vector<pair<ll,ll>>
    	#define vvll vector<vector<ll,ll>>
    	#define mp make_pair
    	#define SMIN(x,y) x=min(x,y)
    	#define SMAX(x,y) x=max(x,y)
    	#define RNG(j,l,r) for(int j=l;j<r;j++)
    	#define REVRNG(j,l,r) for(int j=r-1;j>=l;j--)
     
    	#ifdef MYDEBUG
    	#define D(x) {cerr << #x << " = " << x endl;}
    	#define D2(x, y) {cerr << #x << " = " << x << "/t" << #y << " = " << y endl;}
    	#define DT(t,x) {cerr<<t<<"\t"<<#x<<" = "<<x endl;}
    	#define DIT(cont) {cerr<<"container: " <<#cont endl<<"\t"; for(auto x: cont){cerr<<x<<" ";} cerr endl;}
    	#define DITlmd(cont,lmd) {cerr<<"container: " <<#cont endl<<"\t"; for(auto x: cont){cerr<<lmd(x)<<" ";} cerr endl;}
    	#define DARR(arr,n) {cerr<<"array :"<<#arr endl <<"\t" ; FOR(i,n){cerr<<arr[i]<<" ";} cerr endl;}
    	#define DARRlmd(arr,n,lmd) {cerr<<"array :"<<#arr endl <<"\t" ; FOR(i,n){cerr<<lmd(arr[i])<<" ";} cerr endl;}
    	#define TT(tex) cerr<<tex endl;
    	#else
    	#define D(x)
    	#define D2(x, y)
    	#define DT(t,x)
    	#define DIT(cont)
    	#define DITlmd(cont,lmd)
    	#define DARR(arr,n)
    	#define DARRlmd(arr,n,lmd)
    	#define TT(tex)
    	#endif
    #endif

	
     
    void solve()
    {
    	// code
		int n; cin>>n;
		
		ll res=0;

		vll a(n),b(n-1);

		FOR(i,n) cin>>a[i];

		for(int el:a) res+=el;


		while(a.size()>1){
			int s=a.size();
			b.resize(s-1);
			ll value=0;
		

			FOR(i,s-1){
				b[i]=a[i]-a[i+1];
			}
			for(ll el :b) value+=el;
			res=max(res,abs(value));

			swap(a,b);


		}

		cout<<res endl;

		


    
    	return;
    }
     
    int main()
    {
        cin.tie(0);
        cout.sync_with_stdio(0);
    	int _;
    	cin >> _;
    	for (int t = 1; t <= _; t++)
    	{
    		#ifdef MYDEBUG
    			cerr << "______________________ testcsase = " << t endl;
    		#endif
    		solve();
    	}
     
    	return 0;
    }