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basic-calculator.cc
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basic-calculator.cc
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class Solution {
public:
//check
int calculate(string s) {
stack<int> operands;
stack<char> operators;
for(int i = s.length() - 1;i >= 0;i--) {
if (s[i] == '+' || s[i] == '-' || s[i] == ')') {
operators.push(s[i]);
} else if (s[i] >= '0' && s[i] <= '9') {
int j = i;
while(j >= 0 && (s[j] >= '0' && s[j] <= '9')) {
j--;
}
operands.push(stoi(s.substr(j + 1, i - j)));
i = j+1;
cout << operands.top() << endl;
} else if (s[i] == '(') {
while(operators.top() != ')') {
calc(operands, operators);
}
operators.pop();
}
}
while(operands.size() != 1) {
calc(operands, operators);
}
return operands.top();
}
void calc(stack<int>& operands, stack<char>& operators) {
int op1 = operands.top();
operands.pop();
int op2 = operands.top();
operands.pop();
if (operators.top() == '+') operands.push(op1 + op2);
else operands.push(op1 - op2);
operators.pop();
}
};