What is wrong with my code below for the problem: RPNEVAL - Evaluate simple RPN expression https://www.spoj.com/problems/RPNEVAL/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int op_add = 0; // addition
const int op_sub = 1; // subtraction
const int op_mul = 2; // multiplication
const int op_div = 3; // division
const double INF = 1.0 * INT_MAX;
double getOpRes(vector<double> &stk, const int op) {
if(stk.empty()) return INF;
else if(stk.size() == 1) {
stk.pop_back();
return INF;
}
double b = stk.back();
stk.pop_back();
double a = stk.back();
stk.pop_back();
if(op == op_add) return a+b;
if(op == op_sub) return a-b;
if(op == op_mul) return a*b;
if(op == op_div) {
if(b == 0.0) return INF;
else return a/b;
}
return INF;
}
void love() {
string input_exp;
while(getline(cin, input_exp)) {
input_exp += " ";
size_t pos = 0;
vector<double> stk;
bool validexp = true;
string token;
while((pos = input_exp.find(" ")) != string::npos) {
token = input_exp.substr(0, pos);
if(token == "+") {
// addition
double res = getOpRes(stk, op_add);
stk.push_back(res);
}
else if(token == "-") {
// subtraction
double res = getOpRes(stk, op_sub);
stk.push_back(res);
}
else if(token == "*") {
// multiplication
double res = getOpRes(stk, op_mul);
stk.push_back(res);
}
else if(token == "/") {
// division
double res = getOpRes(stk, op_div);
if(res == INF) {
validexp = false;
break;
}
stk.push_back(res);
}
else {
// operand
if(token.length() > 0) {
double tmpd = stod(token);
stk.push_back(tmpd);
}
}
input_exp.erase(0, pos+1);
}
if((stk.size() == 1) && validexp) {
cout << fixed << setprecision(4) << stk.back() << endl;
}
else cout << "ERROR" << endl;
}
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
if(getenv("MY_ONLINE_JUDGE2")) {
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
}
ll t = 1;
//cin >> t;
while(t--) love();
return 0;
}
I am getting the proper output as follows:
ERROR
0.6667
ERROR
-3.5714
for input:
1 2 3 /
2 3 /
3 4 * /
1 2 4 + - 5 * 7 /
