python/TangDou/AcWing_TiGao/T5/QMI/1289_2.cpp

#include <bits/stdc++.h>
using namespace std;
#define int long long

const int MOD = 200907;

// 龟速乘，快速加
int qadd(int a, int b) {
    int res = 0;
    while (b) {
        if (b & 1) res = (res + a) % MOD;
        b >>= 1;
        a = (a + a) % MOD;
    }
    return res;
}

// 快速幂
int qmi(int a, int b) {
    int res = 1;
    while (b) {
        if (b & 1) res = (res * a) % MOD;
        b >>= 1;
        a = a * a % MOD;
    }
    return res;
}

signed main() {
    int T;
    cin >> T;
    while (T--) {
        int a, b, c, k;
        cin >> a >> b >> c >> k;
        if (a + c == b + b)
            cout << (qadd(b - a, k - 1) + a) % MOD << endl; // 为等差即套公式，首项+公差*（项数-1）
        else
            cout << qmi(b / a, k - 1) * a % MOD << endl; // 等比数列用快速幂算末项
    }
}