一元多项式的相关运算

链表实现一元多项式的加法和乘法

#include<bits/stdc++.h>
using namespace std;
typedef struct Node{
    int ceof;
    int exp;
    struct Node* next;
}Node;
Node *read(string s)
{
    Node *head,*middle,*near;
    head=new Node;
    near=new Node;
    head->next=NULL;
    near=head;
    int sign=1,i=0,a=0,b=0;
    while(s[i])
    {
        middle=new Node;
        a=0,b=0,sign=1;
        if(s[i]=='+'){
            i++;
        }
        else if(s[i]=='-'){
            sign=-1;
            i++;
        }
        if(s[i]=='x'){
            a=1;
            i++;
            if(s[i]=='^'){
                i++;
                while(s[i]>='0'&&s[i]<='9'&&i<s.size()){
                    b=b*10+s[i]-'0';
                    i++;
                }
            }
            else if(s[i]!='^'||i>=s.size()){
                b=1;
            }
        }
        else if(s[i]>='0'&&s[i]<='9'){
            while(s[i]>='0'&&s[i]<='9'&&i<s.size()){
                a=a*10+s[i]-'0';
                i++;
            }
            if(s[i]=='x'&&i<s.size()){
                i++;
                if(s[i]=='^'&&i<s.size()){
                    i++;
                    while(s[i]>='0'&&s[i]<='9'){
                        b=b*10+s[i]-'0';
                        i++;
                    }
                }
                else if(s[i]!='^'){
                    b=1;
                }
            }
            else if(i>=s.size()){
                b=0;
            }
        }
        middle->ceof=a*sign;
        middle->exp=b;
        near->next=middle;
        middle->next=NULL;
        near=middle;
    }
    near->next=NULL;
    return head;
}
Node *add_link(Node*p1,Node *p2)
{
    Node *pr1=new Node;
    Node *pr2=new Node;
    Node *head=new Node;
    Node *middle;
    Node *near=new Node;
    head->next=NULL;near=head;
    pr1=p1->next;pr2=p2->next;
    while((pr1)&&(pr2)){
        middle=new Node;
        if(pr1->exp==pr2->exp){
            middle->exp=pr1->exp;
            middle->ceof=pr1->ceof+pr2->ceof;
            pr1=pr1->next;
            pr2=pr2->next;
        }
        else if(pr1->exp>pr2->exp){
            middle->exp=pr1->exp;
            middle->ceof=pr1->ceof;
            pr1=pr1->next;
        }
        else {
            middle->exp=pr2->exp;
            middle->ceof=pr2->ceof;
            pr2=pr2->next;
        }
        near->next=middle;
        middle->next=NULL;
        near=middle;
    }
    if(!pr2&&pr1){
        while(pr1){
            middle=new Node;
            middle->exp=pr1->exp;
            middle->ceof=pr1->ceof;
            near->next=middle;
            middle->next=NULL;
            near=middle;
            pr1=pr1->next;
        }
    }
    else if(pr2&&!pr1){
        while(pr2){
            middle=new Node;
            middle->exp=pr2->exp;
            middle->ceof=pr2->ceof;
            near->next=middle;
            middle->next=NULL;
            near=middle;
            pr2=pr2->next;
        }
    }
    near->next=NULL;
    return head;
}
Node *mul(Node *p1,Node *p2)
{
    Node *pr1=new Node;
    Node *pr2=new Node;
    Node *head=new Node;
    Node *near=new Node;
    head->next=NULL;
    near=head;
    Node* middle;
    pr1=p1->next,pr2=p2->next;
    while(pr2){
        middle=new Node;
        middle->ceof=pr1->ceof*pr2->ceof;
        middle->exp=pr1->exp+pr2->exp;
        near->next=middle;
        middle->next=NULL;
        near=middle;
        pr2=pr2->next;
    }
    Node *r=new Node;
    r=head;
    //while(r=r->next) cout<<r->ceof<<" "<<r->exp<<endl;
    near->next=NULL;
    pr2=p2;
    while(pr1=pr1->next){
        pr2=p2;
        while(pr2=pr2->next){
            //cout<<pr1->ceof<<" "<<pr2->ceof<<endl;
            //cout<<pr1->exp<<" "<<pr2->exp<<endl;
            Node* root=new Node;
            middle=new Node;
            middle->exp=pr1->exp+pr2->exp;
            middle->ceof=(pr1->ceof)*(pr2->ceof);
            root=head;
            while(root=root->next){
                if(root->next!=NULL){
                    if(root->exp>middle->exp&&root->next->exp<middle->exp){
                        middle->next=root->next;
                        root->next=middle;
                        break;
                    }
                    else if(root->exp==middle->exp){
                        root->ceof=middle->ceof+root->ceof;
                        break;
                    }
                }
                else if(root->next==NULL){
                    if(root->exp>middle->exp){
                        middle->next=NULL;
                        root->next=middle;
                        break;
                    }
                    else if(root->exp== middle->exp){
                        root->ceof=middle->ceof+root->ceof;
                        break;
                    }
                }
            }
        }
    }
    return head;
}
void printt(Node *pr)
{
    Node *pd=new Node;
    pd=pr;
    while(pd=pd->next){
        if(pd->ceof!=0){
            if(abs(pd->ceof)!=1){
                if(pd->ceof>0) cout<<"+";
                cout<<pd->ceof;
            }
            else{
                    if(pd->ceof==1){
                        cout<<"+";
                        if(pd->next==NULL&&pd->exp==0) cout<<pd->ceof;
                    }
                    else if(pd->ceof==-1){
                        if(pd->next==NULL&&pd->exp==0) cout<<pd->ceof;
                        else cout<<"-";
                    }
            }
        if(pd->exp!=0){
                if(pd->exp==1) cout<<"x";
                else cout<<"x"<<"^"<<pd->exp;
            }
        }
    }
    cout<<endl;
}
int main()
{
    string s1,s2;
    cin>>s1>>s2;cin.get();
    Node *h1=read(s1);
    Node *h2=read(s2);
    Node *hh=add_link(h1,h2);
    Node *hhh=mul(h1,h2);
    printt(hhh);
    //printt(hh);
}