# LeetCode - 2961. Double Modular Exponentiation
### 題目網址：https://leetcode.com/problems/double-modular-exponentiation/
###### tags: `LeetCode` `Medium` `模擬` `快速冪`

/*
    -LeetCode format-
    Problem: 2961. Double Modular Exponentiation
    Difficulty: Medium
    
    by Inversionpeter
*/



int FastPower(int base, int power, int mod) {
    int answer = 1, buffer = base;
    while (power) {
        if (power & 1) {
            answer = ((long long)answer * buffer) % mod;
        }
        buffer = ((long long)buffer * buffer) % mod;
        power >>= 1;
    }
    return answer;
}

class Solution {
public:
    vector<int> getGoodIndices(vector<vector<int>>& variables, int target) {
        vector <int> goodies;
        for (int i = 0; i != variables.size(); ++i) {
            if (FastPower(FastPower(variables[i][0], variables[i][1], 10), variables[i][2], variables[i][3]) == target) {
                goodies.push_back(i);
            }
        }
        return goodies;
    }
};