高精度乘法

  

   

    

     

    
    

     

      #include <iostream>
     
    
   

    

     

    
    

     

      #include <vector>
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      using namespace std;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      vector<int> mul(vector<int> &A, int b)
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     

          vector<int> C;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    int t = 0;
     
    
   

    

     

    
    

     
    for (int i = 0; i < A.size() || t; i ++ )
     
    
   

    

     

    
    

     

          {
     
    
   

    

     

    
    

     
        if (i < A.size()) t += A[i] * b;
     
    
   

    

     

    
    

     

              C.push_back(t % 10);
     
    
   

    

     

    
    

     

              t /= 10;
     
    
   

    

     

    
    

     

          }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    while (C.size() > 1 && C.back() == 0) C.pop_back();
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    return C;
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      int main()
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     

          string a;
     
    
   

    

     

    
    

     
    int b;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          cin >> a >> b;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

          vector<int> A;
     
    
   

    

     

    
    

     
    for (int i = a.size() - 1; i >= 0; i -- ) A.push_back(a[i] - '0');
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    auto C = mul(A, b);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    for (int i = C.size() - 1; i >= 0; i -- ) printf("%d", C[i]);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    return 0;
     
    
   

    

     

    
    

     

      }
     
    
  
 

同样，模拟即可，注意本题是高精*低精。

文章来源: blog.csdn.net，作者：irrationality，版权归原作者所有，如需转载，请联系作者。

原文链接：blog.csdn.net/weixin_54227557/article/details/120595091