LC 946. Validate Stack Sequences (Rust Stack)

Author: raul-sauco

README.md

@@ -337,7 +337,7 @@ Solutions to LeetCode problems. The first column links to the problem in LeetCod
 | [936. Stamping The Sequence][lc936]                                                           | 🔴 Hard    | [![python](res/py.png)][lc936py]                                                                      |
 | [938. Range Sum of BST][lc938]                                                                | 🟢 Easy    | [![python](res/py.png)][lc938py]                                                                      |
 | [944. Delete Columns to Make Sorted][lc944]                                                   | 🟢 Easy    | [![python](res/py.png)][lc944py]                                                                      |
-| [946. Validate Stack Sequences][lc946]                                                        | 🟠 Medium  | [![python](res/py.png)][lc946py]                                                                      |
+| [946. Validate Stack Sequences][lc946]                                                        | 🟠 Medium  | [![python](res/py.png)][lc946py] [![rust](res/rs.png)][lc946rs]                                       |
 | [947. Most Stones Removed with Same Row or Column][lc947]                                     | 🟠 Medium  | [![python](res/py.png)][lc947py]                                                                      |
 | [948. Bag of Tokens][lc948]                                                                   | 🟠 Medium  | [![python](res/py.png)][lc948py]                                                                      |
 | [953. Verifying an Alien Dictionary][lc953]                                                   | 🟢 Easy    | [![python](res/py.png)][lc953py] [![rust](res/rs.png)][lc953rs]                                       |
@@ -1175,6 +1175,7 @@ Solutions to LeetCode problems. The first column links to the problem in LeetCod
 [lc944py]: leetcode/delete-columns-to-make-sorted.py
 [lc946]: https://leetcode.com/problems/validate-stack-sequences/
 [lc946py]: leetcode/validate-stack-sequences.py
+[lc946rs]: leetcode/validate-stack-sequences.rs
 [lc947]: https://leetcode.com/problems/most-stones-removed-with-same-row-or-column/
 [lc947py]: leetcode/most-stones-removed-with-same-row-or-column.py
 [lc948]: https://leetcode.com/problems/bag-of-tokens/

leetcode/validate-stack-sequences.rs

@@ -0,0 +1,48 @@
+// 946. Validate Stack Sequences
+// 🟠 Medium
+//
+// https://leetcode.com/problems/validate-stack-sequences/
+//
+// Tags: String - Stack - Simulation
+
+struct Solution;
+impl Solution {
+    /// Use an extra stack of memory and simulate the operations that took
+    /// place, push the next element, then, while the top of the stack matches
+    /// the next element that needs to be popped, pop it.
+    ///
+    /// Time complexity: O(n) - We visit each element on the pushed array and
+    /// do amortized O(1) for each.
+    /// Space complexity: O(n) - The stack can grow to the same size as the
+    /// input.
+    ///
+    /// Runtime 0 ms Beats 100%
+    /// Memory 2.1 MB Beats 90%
+    pub fn validate_stack_sequences(pushed: Vec<i32>, popped: Vec<i32>) -> bool {
+        let mut stack = vec![];
+        let mut pop_idx = 0;
+        for val in pushed {
+            stack.push(val);
+            while !stack.is_empty() && *stack.last().unwrap() == popped[pop_idx] {
+                stack.pop();
+                pop_idx += 1;
+            }
+        }
+        stack.is_empty()
+    }
+}
+
+// Tests.
+fn main() {
+    let tests = [
+        ([1, 2, 3, 4, 5], [4, 5, 3, 2, 1], true),
+        ([1, 2, 3, 4, 5], [4, 3, 5, 1, 2], false),
+    ];
+    for t in tests {
+        assert_eq!(
+            Solution::validate_stack_sequences(Vec::from(t.0), Vec::from(t.1)),
+            t.2
+        );
+    }
+    println!("\x1b[92m» All tests passed!\x1b[0m")
+}