宁波理工邀请赛 c zoj3185解题报告

C - List Operations

Time Limit:1000MS     Memory Limit:32768KB     64bit IO Format:%lld & %llu

Submit  Status

Description

A list is a sequence of zero or more elements, expressed in this form: [a₁, a₂, a₃, ... , a_n], where each a_i is one or more consecutive digits or lowercase letters. i.e. each list begins with a left square bracket, then zero or more elements separated by a single comma, followed by a right square bracket. There will be no whitespace characters (spaces, TABs etc) within a list.

In this problem, we use two list operations: append (++) and remove (--).

1. A ++ B: append elements in B to the end of A.

2. A -- B: remove all the elements in B, from A. If something appears more than once in B, remove it that many times in A. If there are many equal elements in A to choose from, remove them from left to right (until all occurrences are removed, or there is no need to remove more elements).

Your task is to write a calculator, evaluating simple expressions or the form "list1 ++ list2" or "list1 -- list2".

Input

There will be at most 10 expressions, one in each line, each having the form "list1 ++ list2" or "list1 -- list2", with no more than 80 characters in total (not counting the newline character). There will be exactly two spaces in each line: one before and one after the operator. Input ends with a single dot. The input is guaranteed to satisfy the restrictions stated above.

Output

For each expression, print its result on a single line.

Sample Input

[1,2,3] ++ [1,2,3]
[a,b,c,t,d,e,t,x,y,t] -- [t]
[a,b,c,t,d,e,t,x,y,t] -- [t,t,t,t]
[123] ++ [456]
.

Sample Output

[1,2,3,1,2,3]
[a,b,c,d,e,t,x,y,t]
[a,b,c,d,e,x,y]
[123,456]

水题，字符串的处理，容易出错！

#include <iostream>
#include <stdio.h>
#include <string>
#include<list>

using namespace std;

int main()
{
    list<string > q1,q2;
    list<string>::iterator ptr1,ptr2;
    char c;
    string str;
    int flag,temp,j;
    while(scanf("%c",&c)!=EOF)
    {
          if(c=='.')
            break;
          q1.clear();
          q2.clear();
          while((c=getchar())!=EOF)
          {

                if(c==']')
                  break;
                  str="";
                  str+=c;
                  while((c=getchar())!=',')
                  {
                        if(c==']')
                              break;
                        str+=c;
                  }

                q1.push_back(str);
                if(c==']')
                        break;

          }
          getchar();
          if((c=getchar())=='+')
            flag=1;
          else
            flag=0;
          getchar();
          getchar();
          getchar();
         while((c=getchar())!=EOF)
          {

                if(c==']')
                  break;

                  str="";
                  str+=c;
                  while((c=getchar())!=',')
                  { if(c==']')
                              break;
                     str+=c;

                  }

                q2.push_back(str);
               if(c==']')
                        break;

          }
          getchar();
         
          if(flag)
          {
               printf("[");
               temp=0;
              for(ptr1=q1.begin(),j=1;ptr1!=q1.end();ptr1++,j++)
              {
                  if(j!=q1.size())
                  {
                      cout<<*ptr1<<",";
                      temp=1;
                  }

                  else
                  {
                        cout<<*ptr1;
                        temp=1;
                  }

              }

               for(ptr1=q2.begin(),j=1;ptr1!=q2.end();ptr1++,j++)
              {


                  cout<<","<<*ptr1;//这里要特别注意，错了几次

              }

              printf("]\n");
          }
          else
          {

                for(ptr1=q2.begin();ptr1!=q2.end();ptr1++)
                {

                      for(ptr2=q1.begin();ptr2!=q1.end();ptr2++)
                      {
                            if(*ptr1==*ptr2)
                            {
                                  *ptr2="A";
                                 break;
                            }
                      }


                }
                temp=0;
                for(ptr2=q1.end(),ptr2--,j=q1.size();j>=0;ptr2--,j--)
                {
                      if(*ptr2!="A")
                         {
                            temp=j;
                            break;
                         }
                }
                 
                cout<<"[";

                for(ptr1=q1.begin(),j=1;ptr1!=q1.end();ptr1++,j++)
                {

                      if((*ptr1!="A")&&(j!=temp))
                        cout<<*ptr1<<",";
                        else if((*ptr1!="A"))
                              cout<<*ptr1;


                }

                printf("]\n");
          }


    }

    return 0;
}