upload

4/E.cpp

@@ -0,0 +1,68 @@
+#include <iostream>
+#include <vector>
+
+class Heap {
+ private:
+  std::vector<int> heap_;
+
+ public:
+  Heap(std::vector<int>& heap): heap_(heap) {
+    for(int i = 0; i < heap_.size(); ++i) {
+      SiftUp(i);
+    }
+  };
+
+  void SiftUp(int i) {
+    while (i > 0) {
+      if (heap_[i] >= heap_[(i-1)/2]) {
+        return;
+      }
+      std::swap(heap_[i], heap_[(i-1)/2]);
+      i = (i-1)/2;
+    }
+  }
+
+  void SiftDown(int i) {
+    int smallest = i;
+    int left = i * 2 + 1;
+    int right = i * 2 + 2;
+
+    if (left < heap_.size() && heap_[left] < heap_[smallest]) {
+      smallest = left;
+    }
+    if (right < heap_.size() && heap_[right] < heap_[smallest]) {
+      smallest = right;
+    }
+    if (smallest == i) {
+      return;
+    }
+    std::swap(heap_[i], heap_[smallest]);
+    SiftDown(smallest);
+  };
+
+  int ExtractMin() {
+    int element = heap_[0];
+    std::swap(heap_[0], heap_[heap_.size() - 1]);
+    heap_.pop_back();
+    SiftDown(0);
+    return element;
+  }
+};
+
+int main() {
+  int n;
+  std::cin >> n;
+  std::vector<int> array(n);
+
+  for (int i = 0; i < n; ++i) {
+    std::cin >> array[i];
+  }
+
+  Heap heap(array);
+
+  for (int i = 0; i < n; ++i) {
+    std::cout << heap.ExtractMin() << ' ';
+  }
+
+  return 0;
+}