题解 | #四则运算#

// HJ50-2 四则运算.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
#include<iostream>
#include<bits/stdc++.h>

using namespace std;

class Solution {
public:
	int ComputerNum(string& s,int left,int right);
};

int Solution::ComputerNum(string& s,int left,int right)
{
	char op = '+';
	vector<int>dp;
	int sum = 0;
	int num = 0;
	for (int i = left; i <= right; i++)
	{
		if (isdigit(s[i]))
		{
			num = num * 10 + s[i] - '0';
		}
		if (s[i] == '{' || s[i] == '[' || s[i] == '(')
		{
			int layer = 0;
			int j = i;
			while (j <= right)
			{
				if (s[j] == '{' || s[j] == '[' || s[j] == '(')
				{
					layer++;
				}
				else if (s[j] == ')' || s[j] == ']' || s[j] == '}')
				{
					layer--;
					if (layer == 0)
					{
						break;
					}
				}
				j++;
			}
			num=ComputerNum(s, i + 1, j - 1);
			i = j + 1;
		}
		if (!isdigit(s[i]) || i == right)
		{
			switch (op)
			{
			case '+':dp.push_back(+num); break;
			case '-':dp.push_back(-num); break;
			case '*':dp.back() *= num; break;
			case '/':dp.back() /= num; break;
			}
			op = s[i];
			num = 0;
		}
	}
	int res = 0;
	for (auto c : dp)
	{
		res += c;
	}
	return res;
}

int main()
{
	Solution a;
	string s;
	while (getline(cin, s))
	{
		cout << a.ComputerNum(s,0,s.size()-1) << endl;
	}
	return 0;
}