feat: add more

Author: gengjiawen

stack/_0150_evaluate_reverse_polish_notation.rs

@@ -0,0 +1,83 @@
+// https://leetcode.com/problems/evaluate-reverse-polish-notation
+//
+// Evaluate the value of an arithmetic expression in [Reverse Polish Notation](http://en.wikipedia.org/wiki/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:** 9
+// **Explanation:** ((2 + 1) * 3) = 9
+// ```
+//
+// **Example 2:**
+//
+// ```
+// **Input:** tokens = ["4","13","5","/","+"]
+// **Output:** 6
+// **Explanation:** (4 + (13 / 5)) = 6
+// ```
+//
+// **Example 3:**
+//
+// ```
+// **Input:** tokens = ["10","6","9","3","+","-11","*","/","*","17","+","5","+"]
+// **Output:** 22
+// **Explanation:** ((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<sup>4</sup>`
+// *   `tokens[i]` is either an operator: `"+"`, `"-"`, `"*"`, or `"/"`, or an integer in the range `[-200, 200]`.
+
+pub fn eval_rpn(tokens: Vec<String>) -> i32 {
+    let mut stack = Vec::new();
+    for token in tokens {
+        if token == "+" {
+            let a = stack.pop().unwrap();
+            let b = stack.pop().unwrap();
+            stack.push(a + b);
+        } else if token == "-" {
+            let a = stack.pop().unwrap();
+            let b = stack.pop().unwrap();
+            stack.push(b - a);
+        } else if token == "*" {
+            let a = stack.pop().unwrap();
+            let b = stack.pop().unwrap();
+            stack.push(a * b);
+        } else if token == "/" {
+            let a = stack.pop().unwrap();
+            let b = stack.pop().unwrap();
+            stack.push(b / a);
+        } else {
+            stack.push(token.parse::<i32>().unwrap());
+        }
+    }
+    return stack.pop().unwrap();
+}
+
+#[test]
+pub fn t1() {
+    assert_eq!(
+        eval_rpn(
+            vec!["2", "1", "+", "3", "*"]
+                .iter()
+                .map(|x| x.to_string())
+                .collect()
+        ),
+        9
+    );
+}

stack/lib.rs

@@ -2,6 +2,7 @@
 
 mod _0020_valid_parentheses;
 mod _0022_generate_parentheses;
+mod _0150_evaluate_reverse_polish_notation;
 mod _0155_min_stack;
 mod _0739_daily_temperatures;
 mod _1598_crawler_log_folder;