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In this post, you will find the solution for the **Evaluate Reverse Polish Notation** **in C++, Java & Python-LeetCode problem**. We are providing the **correct and tested solutions** to coding problems present on **LeetCode**. If you are not able to solve any problem, then you can take help from our Blog/website.

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** Link for the Problem** – Evaluate Reverse Polish Notation– LeetCode Problem

Evaluate Reverse Polish Notation– LeetCode Problem

**Problem:**

Evaluate the value of an arithmetic expression in Reverse Polish Notation.

Valid operators are `+`

, `-`

, `*`

, and `/`

. Each operand may be an integer or another expression.

**Note** that division between two integers should truncate toward zero.

It is guaranteed that the given RPN expression is always valid. That means the expression would always evaluate to a result, and there will not be any division by zero operation.

**Example 1:**

Input:tokens = ["2","1","+","3","*"]Output:9Explanation:((2 + 1) * 3) = 9

**Example 2:**

Input:tokens = ["4","13","5","/","+"]Output:6Explanation:(4 + (13 / 5)) = 6

**Example 3:**

Input:tokens = ["10","6","9","3","+","-11","*","/","*","17","+","5","+"]Output:22Explanation:((10 * (6 / ((9 + 3) * -11))) + 17) + 5 = ((10 * (6 / (12 * -11))) + 17) + 5 = ((10 * (6 / -132)) + 17) + 5 = ((10 * 0) + 17) + 5 = (0 + 17) + 5 = 17 + 5 = 22

**Constraints:**

`1 <= tokens.length <= 10`

^{4}`tokens[i]`

is either an operator:`"+"`

,`"-"`

,`"*"`

, or`"/"`

, or an integer in the range`[-200, 200]`

.

Evaluate Reverse Polish Notation– LeetCode Solutions

Evaluate Reverse Polish Notation Solution in C++:

class Solution { public: int evalRPN(vector<string>& tokens) { stack<int> stack; const unordered_map<string, function<int(int, int)>> op{ {"+", plus<int>()}, {"-", minus<int>()}, {"*", multiplies<int>()}, {"/", divides<int>()}}; for (const string& token : tokens) if (op.count(token)) { const int b = stack.top(); stack.pop(); const int a = stack.top(); stack.pop(); stack.push(op.at(token)(a, b)); } else { stack.push(stoi(token)); } return stack.top(); } };

Evaluate Reverse Polish Notation Solution in Java:

class Solution { public int evalRPN(String[] tokens) { Stack<Integer> stack = new Stack<Integer>(); for (final String token : tokens) switch (token) { case "+": stack.push(stack.pop() + stack.pop()); break; case "-": stack.push(-stack.pop() + stack.pop()); break; case "*": stack.push(stack.pop() * stack.pop()); break; case "/": final int b = stack.pop(); final int a = stack.pop(); stack.push(a / b); break; default: stack.push(Integer.parseInt(token)); } return stack.peek(); } }

Evaluate Reverse Polish Notation Solution in Python:

class Solution: def evalRPN(self, tokens: List[str]) -> int: stack = [] operators = { '+': lambda a, b: a + b, '-': lambda a, b: a - b, '*': lambda a, b: a * b, '/': lambda a, b: int(a / b), } for token in tokens: if token in operators: b = stack.pop() a = stack.pop() stack.append(operators[token](a, b)) else: stack.append(int(token)) return stack[0]