数据结构题集（严蔚敏）2.39 稀疏多项式

数据结构  稀疏多项式：各项的最高次幂相差很大，很稀疏的意思。

struct PolyTerm{int coef;int exp;};struct SqPoly{PolyTerm *data;int last;};float GetValue_SqPoly(SqPoly P,int x0)//求升幂顺序存储的稀疏多项式的值 {float exx=1.0,sum=0;int ex=0;PolyTerm *p=P.data;while(p->coef){while(ex<p->exp){exx*=x0;++ex;}sum+=p->coef*exx;++p;}return sum;}//时间复杂度O(m*e(m))void Subtract_SqPoly(SqPoly P1,SqPoly P2,SqPoly &P3)//求稀疏多项式 P1 减 P2 的差式 P3 {   PolyTerm *p,*q,*r;    p=P1.data;q=P2.data;r=P3.data;   while(p->coef&&q->coef)   {     if(p->exp<q->exp)     {       r->coef=p->coef;       r->exp=p->exp;       p++;r++;     }     else if(p->exp<q->exp)     {       r->coef=-q->coef;       r->exp=q->exp;       q++;r++;     }     else     {       if((p->coef-q->coef)!=0) //只有同次项相减不为零时才需要存入 P3 中       {         r->coef=p->coef-q->coef;         r->exp=p->exp;r++;       }//if       p++;q++;     }//else   }//while   while(p->coef) //处理 P1 或 P2 的剩余项   {     r->coef=p->coef;     r->exp=p->exp;     p++;r++;   }   while(q->coef)   {     r->coef=-q->coef;     r->exp=q->exp;     q++;r++;   }}//Subtract_SqPoly 

typedef struct PolyNode {PolyTerm data;struct PolyNode *next;} PolyNode, *PolyLink;typedef PolyLink LinkedPoly;void QiuDao_LinkedPoly(LinkedPoly &L)//对有头结点循环链表结构存储的稀疏多项式 L 求导 {   PolyNode *p=L->next;   if(!p->data.exp)   {     L->next=p->next;p=p->next; //跳过常数项   }   while(p!=L)   {     p->data.coef*=p->data.exp--;//对每一项求导     p=p->next;   } }//QiuDao_LinkedPoly   void Divide_LinkedPoly(LinkedPoly &L,LinkedPoly &A,LinkedPoly &B)//把循环链表存储的稀疏多项式 L 拆成只含奇次项的 A 和只含偶次项的 B {   PolyNode *p=L->next;   A=(PolyNode*)malloc(sizeof(PolyNode));   B=(PolyNode*)malloc(sizeof(PolyNode));   PolyNode *pa=A;PolyNode *pb=B;   while(p!=L)   {     if(p->data.exp!=2*(p->data.exp/2))     {       pa->next=p;pa=p;     }     else     {       pb->next=p;pb=p;     }     p=p->next;   }//while   pa->next=A;pb->next=B;   }//Divide_LinkedPoly