单向链表应用

来源：互联网发布：英雄联盟辅助软件编辑：程序博客网时间：2024/05/18 03:32

给出一个四则运算表达式，其中每个数字均为小于等于9且大于等于0。不考虑溢出，计算结果。表达式如"1+2*3-6+5-8/2+1+7"。

#include <iostream>using namespace std;struct Node{    int value;    Node *next;};int calculate(char a[]){    if (NULL == a)    {        return 0;    }    Node *head = new Node();    head->value = a[0] - '0';    Node *p = head;    char *q = (a + 1);    while ('\0' != *q)    {        Node *temp = new Node();        if (*q <= '9' && *q >= '0')        {            temp->value = *q - '0';        }        else         {            temp->value = *q;        }        p->next = temp;        p = p->next;        q++;    }    p->next = NULL;    // 计算乘除    p = head;    while (NULL != p)    {        if (p->next != NULL && (p->next->value == '*' || p->next->value == '/'))        {            if (p->next->value == '*')            {                p->value = (p->value) * (p->next->next->value);            }            else            {                p->value = (p->value) / (p->next->next->value);            }            Node *temp = p->next;            p->next = p->next->next->next;            delete temp->next;            delete temp;        }        else         {            p = p->next;        }    }        //计算加减    p = head;    while (NULL != p)    {        if (p->next != NULL && (p->next->value == '+' || p->next->value == '-'))        {            if (p->next->value == '+')            {                p->value = (p->value) + (p->next->next->value);            }            else            {                p->value = (p->value) - (p->next->next->value);            }            Node *temp = p->next;            p->next = p->next->next->next;            delete temp->next;            delete temp;        }        else         {            p = p->next;        }    }    int result = head->value;    delete head;        return result;}