uva442-矩阵链乘

#include<iostream>
#include<cstdio> 
#include<string.h>
#include<stack>
using namespace std;
const int maxNum = 200;
struct Matrix {
    int x, y;
}Mat[maxNum];
stack<Matrix> st;
int main()
{
    int n;
    char s[10000];
    cin >> n;
    for(int i=0; i<n; i++) {
        char a;
        int b, c;
        cin >> a >> b >> c;
        Mat[a].x = b; Mat[a].y = c;
    }
    getchar();
    while(gets(s) != NULL) {
        bool error = false;
        int tot = 0;
        for(int i=0; i<strlen(s); i++) {
            if(isupper(s[i])) {
                st.push(Mat[s[i]]);
            }
            else if(s[i] == ‘)‘) {
                Matrix temp1, temp2;
                temp1 = st.top(); st.pop();
                temp2 = st.top(); st.pop();
                if(temp1.x != temp2.y) { error = true; break; }
                else {
                    Matrix temp;
                    temp.x = temp2.x; temp.y = temp1.y;
                    st.push(temp);
                    tot += temp2.x*temp2.y*temp1.y;
                }
            }
        }
        if(error) cout << "error" << endl;
        else cout << tot << endl;
        while(!st.empty()) st.pop();
    }
    return 0;
}