高精度加法：

AcWing 791. 高精度加法---$\color{red}{海绵宝宝来喽}$ - AcWing

#include 
#include 
using namespace std;
vector add(vector &A, vector &B)
{if (A.size() < B.size()) return add(B, A);//为了方便计算，让A中保存较长的数字， B中保存较短的数字vector C;//保存结果的数组int t = 0;//进位，开始时是0for (int i = 0; i < A.size(); i ++ )//依次计算每一位{t += A[i];//加上 A 的第 i 位上的数字if (i < B.size()) t += B[i];//加上 B 的第 i 位上的数字C.push_back(t % 10); //C 中放入结果t /= 10;//t 更新成进位}if (t) C.push_back(t);//最后如果进位上有数，放进结果数组return C;//返回结果
}int main()
{string a, b;//以字符串形式保存输入的两个整数vector A, B;//保存两个整数的数组cin >> a >> b;//接收输入for (int i = a.size() - 1; i >= 0; i -- ) A.push_back(a[i] - '0');//倒序存储第一个数for (int i = b.size() - 1; i >= 0; i -- ) B.push_back(b[i] - '0');//倒序存储第二个数auto C = add(A, B);//调用加和函数for (int i = C.size() - 1; i >= 0; i -- ) cout << C[i];//倒序输出C中的数字cout << endl;return 0;
}

 高精度减法：

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#include
#include
using namespace std;
const int N = 1e6 +10;
//判断是否有A>=B
bool cmp(vector &A,vector &B)
{if(A.size() != B.size())  return A.size() > B.size();   //位数不同for(int i =A.size() -1;i >= 0;i--){if(A[i] != B[i])return A[i] > B[i];}return true;
}
// C = A - B, 满足A >= B, A >= 0, B >= 0
vector sub(vector &A, vector &B)
{vector C;for (int i = 0, t = 0; i < A.size(); i ++ ){t = A[i] - t;if (i < B.size()) t -= B[i];C.push_back((t + 10) % 10);if (t < 0) t = 1;else t = 0;}while (C.size() > 1 && C.back() == 0) C.pop_back();return C;
}
int main()
{string a,b;vector A,B;cin>>a>>b;for(int i = a.size() - 1;i>=0;i--) A.push_back(a[i] - '0');for(int i = b.size() - 1;i>=0;i--) B.push_back(b[i] - '0');if(cmp(A,B)){auto C = sub(A,B);for(int i = C.size() -1;i>=0;i--) printf("%d",C[i]);}else{auto C = sub(B,A);printf("-");for(int i = C.size() -1;i>=0;i--) printf("%d",C[i]);}return 0;
}  

高精度乘法：

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#include 
#include 
using namespace std;
vector mul(vector &A, int b)
{vector 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 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;
}

高精度除法

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#include 
#include 
#include using namespace std;vector div(vector &A, int b, int &r)
{vector C;r = 0;for (int i = A.size() - 1; i >= 0; i -- ){r = r * 10 + A[i];C.push_back(r / b);r %= b;}reverse(C.begin(), C.end());while (C.size() > 1 && C.back() == 0) C.pop_back();return C;
}
int main()
{string a;vector A;int B;cin >> a >> B;for (int i = a.size() - 1; i >= 0; i -- ) A.push_back(a[i] - '0');int r;auto C = div(A, B, r);for (int i = C.size() - 1; i >= 0; i -- ) cout << C[i];cout << endl << r << endl;return 0;
}