1657B - XY Sequence - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define int long long
#define For(i, s, e) for (ll i = s; i < e; i++)
#define FOR(i, s, e) for (ll i = s; i <= e; i++)
#define FORD(i, s, e) for (ll i = s; i >= e; i--)
#define pb push_back
#define vii vector<ll>
#define makep make_pair
#define vpll vector<pair<ll, ll>>
#define fi first
#define se second
#define sii set<ll>
#define pii pair<int, int>
#define rev(c) reverse(c.begin(), c.end())
#define sortf(c) sort(c.begin(), c.end())
#define sortd(c) sort(c.begin(), c.end(), greater<int>())
#define test()   \
    int test;    \
    cin >> test; \
    while (test--)
#define fast()                        \
    ios_base::sync_with_stdio(false); \
    cin.tie(0);                       \
    cout.tie(0);
#define sqr(n) (n) * (n)
#define len(s) (int)(s.length())
#define re0 return 0
#define re return

int const N2 = 1e4 + 7;
int const N = 1e6 + 7;
int const inf = 1e18 + 7;
int const mod = 1e9 + 7;
char const nl = '\n';

// ! ¸,ø¤º°`°º¤ø,¸¸,ø¤º° [ нvмegy ] °º¤ø,¸¸,ø¤º°`°º¤ø,¸ roadтoнυe

signed main()
{
    fast();

    test() { 
        int n, B, x, y; 
        cin >> n >> B >> x >> y; 
        int sum = 0; 
        int cur = 0, pre = 0; 
        FOR(i, 1, n) { 
            if (pre + x <= B) cur = pre + x;
            else cur = pre - y; 
            sum += cur;
            pre = cur;
        }
        cout << sum << nl;
    }
    return 0;
}