UVA - 442 Matrix Chain Multiplication

#include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <cstring>
#include <string>
#include <algorithm>
#include <string>
#include <set>
#include <functional>
#include <numeric>
#include <sstream>
//#include <stack>
#include <map>
#include <queue>

#define CL(arr, val)    memset(arr, val, sizeof(arr))

#define ll long long
#define inf 0x7f7f7f7f
#define lc l,m,rt<<1
#define rc m + 1,r,rt<<1|1
#define pi acos(-1.0)

#define L(x)    (x) << 1
#define R(x)    (x) << 1 | 1
#define MID(l, r)   (l + r) >> 1
#define Min(x, y)   (x) < (y) ? (x) : (y)
#define Max(x, y)   (x) < (y) ? (y) : (x)
#define E(x)        (1 << (x))
#define iabs(x)     (x) < 0 ? -(x) : (x)
#define OUT(x)  printf("%I64d\n", x)
#define lowbit(x)   (x)&(-x)
#define Read()  freopen("a.txt", "r", stdin)
#define Write() freopen("dout.txt", "w", stdout);
#define N 100005
using namespace std;

struct node
{
    int a,b;
    char c;
}p[30];

bool cmp(node x,node y)
{
    return x.c<y.c;
}

char s[10000],stack[10000]; //栈 

int main()
{
    //Read();
    int n,i,j,k;
    while(~scanf("%d",&n))
    {
        getchar();
        for(i=0;i<n;i++)
        {
            scanf("%c %d %d",&p[i].c,&p[i].a,&p[i].b);
            getchar();
        }
        sort(p,p+n,cmp);
        while(gets(s))
        {
            int l=strlen(s),top,num=0;
            for(i=0,top=0;i<l;i++)
            {
                if(s[i]=='(') stack[top++]=s[i];  
                else if(s[i]>='A'&&s[i]<='Z')  stack[top++]=s[i]; //把不是 右括号的都压入栈
                else if(s[i]==')')
                {
                    for(j=0;j<n;j++) if(stack[top-2]==p[j].c) break;
                    for(k=0;k<n;k++) if(stack[top-1]==p[k].c) break; //找出 编号
                    if(p[j].b!=p[k].a) break; //如果矩阵不能相乘  就跳出
                    num+=p[j].a*p[j].b*p[k].b;
                   // printf("%d\n",num);
                    p[n].a=p[j].a;p[n].b=p[k].b;p[n].c=p[n-1].c+1; //生成一个新的矩阵
                    stack[top-3]=p[n].c;top-=2; //退栈
                    n++;
                }
            }
            if(i<l) printf("error\n");
            else printf("%d\n",num);
        }
    }
    return 0;
}