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@yippee-ki-yay /reddit_135_easy
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For the reddit 135 easy challenge, uses rpn (probably badly implemented), very messy code, I will make a calculator using this method and try to write cleaner code and understand the whole thing better....
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <stack>
#include <vector>
#include <queue>
#include <deque>
#include <string>
#include <sstream>
#include <iostream>
using namespace std;
bool IsOp(char token, vector<char>& op)
{
for(unsigned int i = 0; i < op.size(); ++i)
{
if(token == op[i])
return true;
}
return false;
}
bool IsOp(string token, vector<char>& op)
{
for(unsigned int i = 0; i < op.size(); ++i)
{
string tmp(1, op[i]);
if(tmp == token) return true;
}
return false;
}
double String2Number(string &token)
{
istringstream ss(token);
double num;
ss >> num;
return num;
}
void ParseString(string& input, queue<string>& output, vector<char>& vec)
{
stack<string> op_stack;
string number;
bool presedence = false;
bool in_digit = false;
for(unsigned int i = 0; i < input.length(); ++i)
{
if(isdigit(input[i]))
{
in_digit = true;
number += input[i];
}
if(input[i] == ' ' || i == input.length()-1)
{
if(in_digit == true)
{
output.push(number);
if(presedence == true)
{
string op = op_stack.top();
op_stack.pop();
output.push(op);
presedence = false;
}
in_digit = false;
number.clear();
}
}
if(IsOp(input[i], vec))
{
string tmp(1, input[i]);
op_stack.push(tmp);
if(input[i] == '*')
{
presedence = true;
}
}
}
stack<string> tmp;
while(!op_stack.empty())
{
string op = op_stack.top();
op_stack.pop();
tmp.push(op);
}
while(!tmp.empty())
{
string op = tmp.top();
tmp.pop();
output.push(op);
}
}
double Calculate(queue<string>& output, vector<char> & op)
{
deque <double> numbers;
while(!output.empty())
{
string tmp = output.front();
output.pop();
if(IsOp(tmp, op))
{
int m, l, r = 0;
if(tmp == "*")
{
m = numbers.back();
numbers.pop_back();
l = numbers.back();
numbers.pop_back();
}
else
{
m = numbers.front();
numbers.pop_front();
l = numbers.front();
numbers.pop_front();
}
if(tmp == "+") r = m + l;
if(tmp == "-") r = m - l;
if(tmp == "*") r = m * l;
if(tmp == "*")
numbers.push_back(r);
else
numbers.push_front(r);
}
else
{
numbers.push_back(String2Number(tmp));
}
}
double result = numbers.front();
return result;
}
string Int2String(int t)
{
stringstream ss;
ss << t;
return ss.str();
}
int main()
{
queue<string> out_queue;
vector<char> operators;
operators.push_back('+');
operators.push_back('-');
operators.push_back('*');
srand(time(0));
int M, N;
cin>>M>>N;
while(1)
{
vector<string> r_num;
for(int i = 0; i < 4; i++)
{
int tmp = (rand() % N + M);
r_num.push_back(Int2String(tmp));
}
vector<char> r_ops;
for(int i = 0; i < 3; i++)
r_ops.push_back(operators[rand()%3]);
string expression = r_num[0] + " " + r_ops[0] + " " + r_num[1] + " " + r_ops[1] + " " + r_num[2] \
+" " + r_ops[2] + " " + r_num[3];
cout<<"> "<<expression<<endl;
ParseString(expression, out_queue, operators);
int comp_result = Calculate(out_queue, operators);
int i_result = 0;
string s_result;
cin>>s_result;
if(s_result == "q")
return 0;
i_result = String2Number(s_result);
if(i_result == comp_result)
cout<<"Correct!"<<endl;
}
return 0;
}
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