用合约实现模N算术

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

contract ModularArithmetic {
    function modN(uint256 a, uint256 N) public pure returns (uint256) {
        return a % N;
    }

    function modExp(uint256 base, uint256 exp, uint256 mod) public pure returns (uint256) {
        uint256 result = 1;
        base = base % mod;
        while (exp > 0) {
            if (exp % 2 == 1) { // If exp is odd, multiply base with result
                result = (result * base) % mod;
            }
            exp = exp >> 1; // exp = exp/2
            base = (base * base) % mod; // Change base to base^2
        }
        return result;
    }
}