UVA_442_Matrix_Chain_Multiplication

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <string>
#include <cctype>
#include <stack>
#include <queue>
#include <list>
#include <vector>
#include <map>
#include <set>
#include <sstream>
#include <stdlib.h>
#include <cmath>
#define LL unsigned long long
using namespace std;
typedef struct m{
    char car;
    int r;
    int c;
}Tmat;
Tmat arr[27];

int main() {
 int ro,col,index,aux,n,result;
 char c;Tmat au;
 string cad;
  stack<Tmat> s;
  bool fallo;
  Tmat s1,s2;
  scanf("%d",&n);
  int cont=0;getchar();
  for (int i=0;i<n;i++){
    scanf("%c %d %d",&c,&ro,&col);
    arr[i].car=c;arr[i].r=ro;arr[i].c=col;
        getchar();
  }
  fallo=false;
  while(cin>>cad){
    result=0;index=0;fallo=false;
    n=cad.length();
    if(n==1){printf("0\n");}
    else{
      while(index<=n-1 && !fallo){
        if(isalpha(cad[index])){
            cont=0;
             /*busco el correspondiente car*/
             while(arr[cont].car!=cad[index]){
                cont++;
             }
             au=arr[cont];
            s.push(au);
            index++;
        }else if(cad[index]==')'){
            s1=s.top();s.pop();s2=s.top();s.pop();
            if(s1.r!=s2.c){fallo=true;continue;}
            else{
             result+=(s1.c*s1.r*s2.r);
             aux=s1.c;
             s1.r=s2.r; s1.c=aux;
             s.push(s1);
             index++;
             }
        }else{
            index++;
        }
    }
       if(!fallo){
    printf("%d\n",result);
       }else printf("error\n");
    }

    getchar();
  }
  return 0;
}