Derivation of one-element polynomial

/* Unary polynomial derivation (25) Design function to find the derivative of a polynomial. Input format: input polynomial non-0 coefficients and exponents in exponential degradation (absolute values are integers not exceeding 1000). The numbers are separated by a space. Output format: Outputs the coefficients and exponents of the derivative polynomial not 0 in the same format as the input. The numbers are separated by a space, but cannot have extra spaces at the end. Note that the exponent and coefficients for the "0 polynomial" are 0, but are expressed as "0 0".  Input Sample: 3 4-5 2 6 1-2 0 i.e. 3x^4-5x^2 + 6x-2 Output Sample: 12 3-10 1 6 0 i.e. 12x^3-10x + 6-0 derivative: The derivative of ax^n is a*nx^ (n-1), which is the output in the case The derivative of the A*n n-1 constant is 0*/#pragma once#include<vector> #include <sstream> #include <iostream> #include <    string>using namespace std;struct item{int e;  int n;    };void Input (Vector<item>&vec) {string line;    Item it;    int num;    bool BN = true;    Getline (CIN, line, ' \ n ');    Istringstream stream (line);        while (stream >> num) {static int i = 0;        if (bN) IT.N = num;        else IT.E = num;        if (++i%2==0) vec.push_back (IT);    BN =!bn;    }}//merge similar top void comb (Vector<item>&a, vector<item>&b) {int size = A.size ();    int i;  for (i = 0; i < size-1; ++i) {if (A[I].E = = A[i + 1].e)      {A[I+1].N + = A[I].N;        } else {if (A[I].N! = 0) B.push_back (a[i]); }}//The last missing if (A[I].N! = 0) B.push_back (A[i]);}    void Output (VECTOR&LT;ITEM&GT;&AMP;VEC) {int size = Vec.size (); if (size = = 1 && vec[0].e = = 0 && vec[0].n==0) | | size = = 0) {cout << "0 0" << end        L    Return        } for (int i = 0; i < size; ++i) {if (vec[i].e = = 0) cout << ' 0 ';        else if (vec[i].e-1 = = 0) cout << VEC[I].N;            else {cout << VEC[I].N * vec[i].e << ';        cout << vec[i].e-1;    } if (i! = size-1) cout << '; } cout << Endl;}    void Run () {Vector<item>vec, der;    Input (VEC);    Comb (Vec, der); Output (der);}    int main (void) {Run (); return 0;}

Derivation of one-element polynomial