PAT甲级 1002. A+B for Polynomials (25)

[m0_37456841]

测试数据中有一组是错的，但不知道错在了哪里。。。

#include<stdio.h>
#include<stdlib.h>
typedef struct Node{
	double exp,coef;
	struct Node *next;
}*LinkList,Node;
LinkList createList(){
	LinkList L;
	L=(Node *)malloc(sizeof(Node));
	L->next=NULL;
	return L;
}
void insert(LinkList L,double exp,double coef){
	Node *p,*pre,*s;
	p=L->next;
	pre=L;
	while(p!=NULL&&p->exp>exp){
		pre=p;
		p=p->next;
	}
	s=(Node*)malloc(sizeof(Node));
	s->coef=coef;
	s->exp=exp;
	s->next=pre->next;
	pre->next=s;
}
void plus(LinkList LA,LinkList LB)
{
	Node *p1,*p2,*pre,*temp;
	pre=LA;
	p1=LA->next;
	p2=LB->next;
	LA->next=NULL;
	while(p1!=NULL&&p2!=NULL){
		if(p1->exp>p2->exp){
			pre->next=p1;
			pre=p1;
			p1=p1->next;
		}
		else if(p1->exp<p2->exp){
			pre->next=p2;
			pre=p2;
			p2=p2->next;
		}
		else if(p1->exp==p2->exp){
			p1->coef=p1->coef+p2->coef;
			if(p1->coef!=0){
				pre->next=p1;
				pre=p1;
				p1=p1->next;
				temp=p2;
				p2=p2->next;
				free(p2);
			}
			else if(p1->coef==0){
				temp=p1;
				p1=p1->next;
				free(temp);
				temp=p2;
				p2=p2->next;
				free(temp);
			}
		}
	}
	if(p1!=NULL){
		pre->next=p1;
	}
	else if(p2!=NULL){
		pre->next=p2;
	}
	free(LB);
	
}
int Listlength(LinkList L)
{
	int k=0;
	Node *p;
	p=L->next;
	while(p!=NULL){
		k++;
		p=p->next;
	}
	return k;
}
void output(LinkList L){
	Node *p;
	p=L->next;
	while(p!=NULL){
		printf(" %.0lf %.1lf",p->exp,p->coef);
		p=p->next;
	}
	printf("\n");
}
int main()
{
	int a,b,sum;
	double exp,coef;
	LinkList LA;
	LinkList LB;
	LB=createList();
	LA=createList();
	scanf("%d",&a);
	while(a!=0){
		scanf("%lf %lf",&exp,&coef);
		insert(LA,exp,coef);
		a--;
	}
	scanf("%d",&b);
	while(b!=0){
		scanf("%lf %lf",&exp,&coef);
		insert(LB,exp,coef);
		b--;
	}
	plus(LA,LB);
	sum=Listlength(LA);
	printf("%d",sum);
	output(LA);
	return 0;
}

[m0_37456841]

[自信男孩]

#include<stdio.h>
#include<stdlib.h>

typedef struct Node{
    double exp,coef;
    struct Node *next;
}*LinkList,Node;

LinkList createList(void)
{
    LinkList L;
    L = (Node *)malloc(sizeof(Node));
    L->next = NULL;
    return L;
}
void insert(LinkList L,double exp,double coef)
{
    Node *p,*pre,*s;
    p = L->next;
    pre = L;
    while(p && p->exp > exp){
        pre = p;
        p = p->next;
    }
    s = (Node*)malloc(sizeof(Node));
    s->coef = coef;
    s->exp = exp;
    s->next = pre->next;
    pre->next = s;
}
void plus(LinkList LA, LinkList LB)
{
    Node *p1,*p2,*pre,*temp;
    pre = LA;
    p1 = LA->next;
    p2 = LB->next;
    LA->next = NULL;
    while(p1 && p2){
        if(p1->exp > p2->exp){
            pre->next = p1;
            pre = p1;
            p1 = p1->next;
        }
        else if(p1->exp < p2->exp){
            pre->next = p2;
            pre = p2;
            p2 = p2->next;
        }
        else if(p1->exp == p2->exp){
            p1->coef = p1->coef + p2->coef;
            if(p1->coef != 0){
                pre->next = p1;
                pre = p1;
                p1 = p1->next;
                temp = p2;
                p2 = p2->next;
                free(temp);   /* free temp not p2*/
                //free(p2);
            } else if(p1->coef == 0){
                temp = p1;
                p1 = p1->next;
                free(temp);
                temp = p2;
                p2 = p2->next;
                free(temp);
            }
        }
    }
    if(p1){
        pre->next = p1;
    }
    else if(p2){
        pre->next=p2;
    }
    free(LB);

}
int Listlength(LinkList L)
{
    int k=0;
    Node *p;

    p = L->next;
    while(p){
        k++;
        p = p->next;
    }

    return k;
}
void output(LinkList L)
{
    Node *p;
    p = L->next;
    while(p){
        printf(" %.0lf %.1lf ",p->exp,p->coef);
        p = p->next;
    }
    printf("\n");
}
int main(void)
{
    int a,b,sum;
    double exp,coef;
    LinkList LA;
    LinkList LB;

    LB = createList();
    LA = createList();
    scanf("%d", &a);
    while(a != 0){
        scanf("%lf %lf", &exp, &coef);
        insert(LA, exp, coef);
        a--;
    }
    scanf("%d", &b);
    while(b != 0){
        scanf("%lf %lf",&exp, &coef);
        insert(LB,exp,coef);
        b--;
    }
    plus(LA,LB);
    sum = Listlength(LA);
    printf("%d\n", sum);
    output(LA);
    return 0;
}

代码写的不错，有一个小问题，应该free(temp)，但是你释放的是p2，详见上面的代码； 其他地方也做了修改，但不是逻辑问题，而是个人习惯。比如

while(p1 && p2){

你的判断是这样的：

while(p1!=NULL&&p2!=NULL){

这个地方需要理解的地方是，当p1 == NULL或p2 == NULL 时，则为假