Leetcode-inverse Polish Solution

Calculate the inverse Polish formula:

Valid operations are only+,-,*,/. Each input is an integer or an operator.

Some examples:

  ["2", "1", "+", "3", "*"] -> ((2 + 1) * 3) -> 9  ["4", "13", "5", "/", "+"] -> (4 + (13 / 5)) -> 6

<span style="font-size:14px;">#include<iostream>#include<string>#include<vector>using namespace std;const int Max=100;bool isInt(const string str){    if(str[0]=='+'||(str[0]=='-'&&str.size()==1)||str[0]=='*'||str[0]=='/')   return false;  else return true;}int toInt(string str){   int re=0;   //cout<<"str: "<<str<<endl;   for(int i=0;i<str.size();i++)   {    re = re*10+ str[i]-'0';   }  // cout<<"re: "<<re<<endl;   return re;}int fun(vector<string> &tokens){  double  values[Max]={0};  int k=0;  vector<char> oper;  double result=0;  for(int i=0;i<tokens.size();i++)  {     if(isInt(tokens[i]))     {       values[k++]=toInt(tokens[i]);         }else{      double tmp1=values[--k];      double tmp2=values[--k];      char t = tokens[i][0];      switch(t)      {        case '+': result = tmp2 + tmp1; break;        case '-': result = tmp2 - tmp1; break;        case '*': result = tmp2 * tmp1; break;        case '/': result = tmp2 / tmp1; break;             }        values[k++]=result;     }   }    return result; }int main(){    string str[5]={"4","13","5","/","+"};    vector<string> token(str,str+5);     cout<<fun(token)<<endl;}</span>

An array is used in the code to simulate a stack operation.

Leetcode-inverse Polish Solution