Evaluate Reverse Polish Notation Problem & Solution

#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx,avx2,fma")

static const int _=[]{ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();

class Solution {
public:
  int evalRPN(vector<string>& tokens) {
    stack<int> s;

    for (auto token : tokens) {
      if (token == "+" || token == "-" || token == "*" || token == "/") {
        int a = s.top(); s.pop();
        int b = s.top(); s.pop();

        if (token == "+") {
          s.push(a + b);
        } else if (token == "-") {
          s.push(b - a);
        } else if (token == "*") {
          s.push(a * b);
        } else if (token == "/") {
          s.push(b / a);
        }
      } else {
        s.push(stoi(token));
      }
    }

    return s.top();
  }
};