算法刷题记录：[NOIP2000]计算器的改良（未AC）

题目链接

https://ac.nowcoder.com/acm/contest/19306/1043

题目分析

模拟就完事，代码写的很屎山，估计哪里死循环了，要不就是TLE，明天改。

未AC代码

#include <iostream>
#include <iomanip>
#include <algorithm>

using namespace std;

const int N = 100010;

string equation;

// a:字母，b：数字
// flag：true -> 字母
int main()
{
    cin >> equation;
    // equation = "6a-5+1=2-2a";
    int equal = 0;
    char c;
    for (int i = 0; i < equation.size(); ++ i)
    {
        if (equation[i] == '=') equal = i;
        if (equation[i] >= 97 && equation[i] <= 122) c = equation[i];
    }

    float a = 0, b = 0;
    for (int i = 0; i < equal; ++ i)
    {    
        if (!i && equation[i] != '-')
        {
            int j = i, flag = false, tmp = 0, bit = 1;
            int stk[10], tt = -1;
            if (equation[j] >= 97 && equation[j] <= 122) tmp = 1;
            else 
            {
                while (equation[j] >= '0' && equation[j] <= '9')
                    stk[ ++ tt] = equation[j ++ ] - '0';
            }
            if (equation[j] >= 97 && equation[j] <= 122) flag = true;
            while (tt != -1) tmp += stk[tt -- ] * bit, bit *= 10;
            if (flag) a += tmp;
            else b -= tmp;
            i = j - 1;
        }
        
        if (equation[i] == '-' || equation[i] == '+')
        {
            bool op = true, flag = false;
            if (equation[i] == '-') op = false;
            
            int j = i + 1, tmp = 0, bit = 1;
            int stk[10], tt = -1;
            
            // 开头就是字母的情况
            if (equation[j] >= 97 && equation[j] <= 122) tmp = 1;
            else 
            {
                while (equation[j] >= '0' && equation[j] <= '9')
                    stk[ ++ tt] = equation[j ++ ] - '0';
            }
            
            if (equation[j] >= 97 && equation[j] <= 122) flag = true;
            
            while (tt != -1) 
                tmp += stk[tt -- ] * bit, bit *= 10;

            if (flag)
            {
                if (op) a += tmp;
                else a -= tmp;
            }
            else 
            {
                if (op) b -= tmp;
                else b += tmp;
            }
            
            i = j - 1;
        }
    }
    
    for (int i = equal + 1; i < equation.size(); ++ i)
    {
        if (i == equal + 1 && equation[i] != '-')
        {
            int j = i, flag = false, tmp = 0, bit = 1;
            int stk[10], tt = -1;
            if (equation[j] >= 97 && equation[j] <= 122) tmp = 1;
            else 
            {
                while (equation[j] >= '0' && equation[j] <= '9')
                    stk[ ++ tt] = equation[j ++ ] - '0';
            }
            if (equation[j] >= 97 && equation[j] <= 122) flag = true;
            while (tt != -1) tmp += stk[tt -- ] * bit, bit *= 10;
            if (flag) a -= tmp;
            else b += tmp;
            i = j - 1;
        }
        
        if (equation[i] == '-' || equation[i] == '+')
        {
            bool op = true, flag = false;
            if (equation[i] == '-') op = false;
            
            int j = i + 1, tmp = 0, bit = 1;
            int stk[10], tt = -1;
            
            // 开头就是字母的情况
            if (equation[j] >= 97 && equation[j] <= 122) tmp = 1;
            else 
            {
                while (equation[j] >= '0' && equation[j] <= '9')
                    stk[ ++ tt] = equation[j ++ ] - '0';
            }
            
            if (equation[j] >= 97 && equation[j] <= 122) flag = true;
            
            while (tt != -1) 
                tmp += stk[tt -- ] * bit, bit *= 10;

            if (flag)
            {
                if (op) a -= tmp;
                else a += tmp;
            }
            else 
            {
                if (op) b += tmp;
                else b -= tmp;
            }
            
            i = j - 1;
        }
    }
    cout << c << '=' << fixed << setprecision(3) << b /a << endl;
}