如何在我的代码中实现“ BigInteger to Integer反之亦然”，无法解决不兼容的类型错误

Question

我尝试在Java中使用long类型，效果很好。但是，我想处理大于长值的值，所以我搬到BigInteger，但最后遇到类型不兼容（BigInteger和int）的错误。预先感谢。

import java.io.*;
import java.util.*;
import java.math.BigInteger;
class Main
{
public static BigInteger aryaStarkToWin(int p, int r,BigInteger[][]req_Array) {
    BigInteger a=new BigInteger("1000000007");
    BigInteger b=new BigInteger("0");
    req_Array[p][0]=wins(p, 0, 0, p, r,req_Array) ; 
    BigInteger returnValue= req_Array[p][0];
    returnValue=returnValue.mod(a);
    return returnValue ;
}
public static BigInteger wins(int aryaCounter, int sansaCounter, BigInteger chances, final int p, final int r,BigInteger[][]req_Array) {
      BigInteger a=new BigInteger("1000000007");
       BigInteger b=new BigInteger("0");
       BigInteger c=new BigInteger("1");
       BigInteger d=new BigInteger("-1");
    if(req_Array[aryaCounter][sansaCounter]!=d) {
        return req_Array[aryaCounter][sansaCounter];
    }           
    if (aryaCounter < sansaCounter * p) {                   
        return b;
    }

    if (aryaCounter + sansaCounter == r) {          
        return c;
    }        
    req_Array[aryaCounter][sansaCounter]=(wins(aryaCounter + 1, sansaCounter, chances, p, r,req_Array).mod(a).add(wins(aryaCounter, sansaCounter + 1, chances, p, r,req_Array).mod(a))).mod(a);

    return req_Array[aryaCounter][sansaCounter]; 
}
public static void main(String[] args) {
    int T_cases=0;
    Scanner scany= new Scanner(System.in);
    T_cases=scany.nextInt();
    BigInteger d=new BigInteger("-1");
    while(T_cases-->0) {        
        int no_of_rounds = scany.nextInt();
        BigInteger[][] req_Array = new BigInteger[no_of_rounds+1][no_of_rounds+1];      
        int ptimes=scany.nextInt();
        for(int i=0;i<=no_of_rounds;i++) {
            for(int j=0;j<=no_of_rounds;j++) {
                req_Array[i][j]=d;
            }
        }       
        System.out.println(aryaStarkToWin(ptimes,no_of_rounds,req_Array));              
    }
    scany.close();      
}
}

输入是

2
4 2
2 2

输出必须是

3
1 

但是，我收到错误消息，例如

Main.java:9: error: incompatible types: int cannot be converted to BigInteger
    req_Array[p][0]=wins(p, 0, 0, p, r,req_Array) ; 
1 error

Answer 1

您正在调用以下方法：

req_Array[p][0]=wins(p, 0, 0, p, r,req_Array) ;
                           ^

并且方法签名为：

public static BigInteger wins(int aryaCounter, int sansaCounter, BigInteger chances, final int p, final int r,BigInteger[][]req_Array) {
                                                                 ^^^^^^^^

您可以按如下方式传递的第三个参数：

req_Array[p][0]=wins(p, 0, BigInteger.ZERO, p, r,req_Array) ;

或将方法签名更改为：

public static BigInteger wins(int aryaCounter, int sansaCounter, int chances, final int p, final int r,BigInteger[][]req_Array) {

话虽如此，您没有在方法中利用机会，因此最好摆脱这种机会。