20240518 Finished

src/problem/mod.rs

@@ -135,3 +135,4 @@ mod p56_merge_intervals;
 mod p57_insert_interval;
 mod p452_minimum_number_of_arrows_to_burst_balloons;
 mod p71_simplify_path;
+mod p155_min_stack;

src/problem/p155_min_stack.rs

@@ -0,0 +1,69 @@
+/**
+ * [155] Min Stack
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+use std::{cmp::Reverse, collections::BinaryHeap};
+
+struct MinStack {
+    heap : BinaryHeap<Reverse<i32>>,
+    stack: Vec<i32>
+}
+
+
+/**
+ * `&self` means the method takes an immutable reference.
+ * If you need a mutable reference, change it to `&mut self` instead.
+ */
+impl MinStack {
+
+    fn new() -> Self {
+        MinStack {
+            heap: BinaryHeap::new(),
+            stack: vec![]
+        }
+    }
+    
+    fn push(&mut self, val: i32) {
+        self.heap.push(Reverse(val));
+        self.stack.push(val);
+    }
+    
+    fn pop(&mut self) {
+        let n = self.stack.pop().unwrap_or(0);
+
+        if !self.stack.contains(&n) {
+            self.heap.retain(|i| i.0 != n);
+        }    
+    }
+    
+    fn top(&self) -> i32 {
+        *self.stack.last().unwrap_or(&0)
+    }
+    
+    fn get_min(&self) -> i32 {
+        self.heap.peek().unwrap_or(&Reverse(0)).0
+    }
+}
+
+/**
+ * Your MinStack object will be instantiated and called as such:
+ * let obj = MinStack::new();
+ * obj.push(val);
+ * obj.pop();
+ * let ret_3: i32 = obj.top();
+ * let ret_4: i32 = obj.get_min();
+ */
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_155() {
+    }
+}