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eval_rpn.cpp
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eval_rpn.cpp
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/*
* =====================================================================================
*
* Filename: eval_rpn.cpp
*
* Description: 150. Evaluate Reverse Polish Notation.
* https://leetcode.com/problems/evaluate-reverse-polish-notation/
*
* Version: 1.0
* Created: 02/20/2023 08:14:25
* Revision: none
* Compiler: gcc
*
* Author: [email protected]
* Organization:
*
* =====================================================================================
*/
#include <stack>
#include <string>
#include <vector>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
using std::stack;
using std::string;
using std::vector;
class Solution {
public:
int evalRPN(vector<string>& tokens) {
std::stack<int> nums;
int res = 0;
for (const string& s : tokens) {
const char c = s[0];
if (s.size() == 1 && (c == '+' || c == '-' || c == '*' || c == '/')) {
const int b = nums.top();
nums.pop();
int& a = nums.top();
if (c == '+') {
a += b;
} else if (c == '-') {
a -= b;
} else if (c == '*') {
a *= b;
} else {
a /= b;
}
} else {
nums.push(std::stoi(s));
}
}
return nums.top();
}
};
TEST(Solution, evalRPN) {
vector<std::pair<vector<string>, int>> cases = {
std::make_pair(vector<string>{"2", "1", "+", "3", "*"}, 9),
std::make_pair(vector<string>{"4", "13", "5", "/", "+"}, 6),
std::make_pair(
vector<string>{"10", "6", "9", "3", "+", "-11", "*", "/", "*", "17", "+", "5", "+"}, 22),
};
for (auto& c : cases) {
EXPECT_EQ(Solution().evalRPN(c.first), c.second);
}
}