Merge pull request #6 from stada526/f/1046

1046. Last Stone Weight

src/common/heap.rs

@@ -5,7 +5,7 @@ pub struct MaxHeap {
 impl MaxHeap {
     pub fn new(array: Vec<i32>) -> Self {
         let mut heap = Self { tree: array };
-        for i in 0..(heap.tree.len() / 2) {
+        for i in (0..(heap.tree.len() / 2)).rev() {
             heap.heapify(i)
         }
 
@@ -58,6 +58,10 @@ impl MaxHeap {
             self.heapify(max_index)
         }
     }
+
+    pub fn len(&self) -> usize {
+        return self.tree.len();
+    }
 }
 
 #[cfg(test)]

src/solutions.rs

@@ -1,3 +1,4 @@
+mod s_1046_last_stone_weight;
 mod s_110_balanced_binary_tree;
 mod s_128_longest_consecutive_sequence;
 mod s_143_reorder_list;

src/solutions/s_1046_last_stone_weight.rs

@@ -0,0 +1,35 @@
+use crate::common::heap::MaxHeap;
+
+struct Solution {}
+
+impl Solution {
+    pub fn last_stone_weight(stones: Vec<i32>) -> i32 {
+        let mut max_heap = MaxHeap::new(stones);
+        while max_heap.len() > 1 {
+            let y = max_heap.pop().unwrap();
+            let x = max_heap.pop().unwrap();
+            let diff = y - x;
+            if diff != 0 {
+                max_heap.push(diff)
+            }
+        }
+
+        return if max_heap.len() == 0 {
+            0
+        } else {
+            max_heap.pop().unwrap()
+        };
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test() {
+        let stones = vec![2, 7, 4, 1, 8, 1];
+        let res = Solution::last_stone_weight(stones);
+        assert_eq!(res, 1)
+    }
+}