将两个多项式相加

题目链接：https://pintia.cn/problem-sets/434/problems/5803
  1 #include <stdio.h>
  2 #include <stdlib.h>
  3 
  4 typedef struct PolyNode* PtrToPolyNode;
  5 struct PolyNode {
  6     int Coef;
  7     int Expon;
  8     PtrToPolyNode Next;
  9 };
 10 
 11 typedef struct PolyNode* Polynomial;
 12 
 13 
 14 int Compare(int e1, int e2)
 15 {    //比较两项指数e1和e2，根据大、小、等三种情况分别返回1， -1， 0
 16     if (e1 > e2)
 17         return 1;
 18     else if (e1 < e2)
 19         return -1;
 20     else
 21         return 0;
 22 }
 23 
 24 void Attach(int coef, int expon, Polynomial *PtrRear)
 25 {
 26     Polynomial p = (Polynomial)malloc(sizeof(struct PolyNode));
 27     p -> Coef = coef;
 28     p->Expon = expon;
 29     p->Next = NULL;
 30     (*PtrRear)->Next = p;
 31     *PtrRear = p;
 32 }
 33 
 34 Polynomial PolyAdd(Polynomial P1, Polynomial P2)
 35 {
 36     Polynomial front, rear, temp;
 37     int sum;
 38     front = rear = (Polynomial)malloc(sizeof(struct PolyNode));
 39     while (P1 && P2)
 40     {
 41         switch (Compare(P1->Expon, P2->Expon))
 42         {
 43         case 1:
 44             Attach(P1->Coef, P1->Expon, &rear);
 45             P1 = P1->Next;
 46             break;
 47         case -1:
 48             Attach(P2->Coef, P2->Expon, &rear);
 49             P2 = P2->Next;
 50             break;
 51         case 0:
 52             sum = P1->Coef + P2->Coef;
 53             if (sum)
 54                 Attach(sum, P1->Expon, &rear);
 55             P1 = P1->Next;
 56             P2 = P2->Next;
 57             break;
 58         }
 59     }
 60     while (P1)
 61     {
 62         Attach(P1->Coef, P1->Expon, &rear);
 63         P1 = P1->Next;
 64     }
 65     while (P2)
 66     {
 67         Attach(P2->Coef, P2->Expon, &rear);
 68         P2 = P2->Next;
 69     }
 70     rear->Next = NULL;
 71     temp = front;
 72     front = front->Next;
 73     free(temp);
 74     return front;
 75 }
 76 
 77 Polynomial CreatePoly()
 78 {
 79     int n, coef, expon;
 80     Polynomial front, rear, temp;
 81     
 82     front = rear = (Polynomial)malloc(sizeof(struct PolyNode));
 83     scanf_s("%d", &n);
 84     while (n--)
 85     {
 86         scanf_s("%d %d", &coef, &expon);
 87         Attach(coef, expon, &rear);
 88     }
 89     rear->Next = NULL;
 90     temp = front;
 91     front = front->Next;
 92     free(temp);
 93     return front;
 94 }
 95 
 96 void printPoly(Polynomial P)
 97 {
 98     Polynomial cell;
 99     cell = P;
100     for (cell; cell; cell = cell->Next)
101     {
102         printf("%dX^%d ", cell->Coef, cell->Expon);
103     }
104 }
105 
106 int main()
107 {
108     Polynomial P1, P2, P3;
109     P1 = CreatePoly();
110     P2 = CreatePoly();
111     P3 = PolyAdd(P1, P2);
112     printPoly(P3);
113 
114 }