6-3 矩阵链成 uva 442

较为简单的栈题

思路比较好 

一次ac

1、char word ；word=A；直接  a[word]=xxxx，不用 a[‘word’]=xxxx

#include<bits/stdc++.h>

using namespace std;


struct aaa
{

    int x;
    int y;

}a[1000];

int main()
{
   stack<aaa>k;
  int n;
  cin>>n;getchar();
  for(int i=1;i<=n;i++)
  {
      char word;cin>>word;
      cin>>a[word].x>>a[word].y;

  }

    string s;
    while(getline(cin,s))
    {
        if(s=="")continue;
        if(s.size()==1){printf("0
");continue;}
        int sum=0;int ok=1;
        for(int i=0;i<s.size();i++)
        {
            if(isalpha(s[i])){k.push(a[ s[i] ]);}
            else if(s[i]==')')
            {
                struct aaa x1=k.top();k.pop();
                struct aaa x2=k.top();k.pop();
                struct aaa x3;
                if(x1.x!=x2.y){ok=0;printf("error
");break;}
                sum+=x1.x*x1.y*x2.x;
                x3.x=x2.x;x3.y=x1.y;
                k.push(x3);


            }


        }
        if(ok)printf("%d
",sum);


    }









    return 0;
}