Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;
/*
 * Copyright 2013 Valentyn Kolesnikov
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.math.BigInteger;

public class Main {
    static BigInteger mulmod(BigInteger a, BigInteger b, BigInteger p) {
        BigInteger r = BigInteger.ZERO;
        while (b.compareTo(BigInteger.ZERO) > 0) {
            if (!b.and(BigInteger.ONE).equals(BigInteger.ZERO)) {
                r = addmod(r, a, p);
            }
            b = b.shiftRight(1);
            a = addmod(a, a, p);
        }
        return r;
    }

    static BigInteger addmod(BigInteger a, BigInteger b, BigInteger p) {
        if (p.subtract(b).compareTo(a) > 0) {
            return a.add(b);
        } else {
            return a.add(b).subtract(p);
        }
    }
}