Basic tasks with priority queues in java.

current/algorithms/intersection.cpp

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+#include <algorithm>
+#include <iostream>
+#include <iterator>
+#include <set>
+#include <vector>
+
+int main() {
+  std::set<int> v1{7, 2, 3, 4, 5, 6, 7, 8};
+  std::set<int> v2{5, 7, 9, 7};
+  // sorting is important for lists if we do want all elements of intersections (f.e. if the elements are not unique in both lists)
+  // std::sort(v1.begin(), v1.end());
+  // std::sort(v2.begin(), v2.end());
+
+  std::set<int> v_intersection;
+
+  std::set_intersection(
+      v1.begin(), v1.end(), 
+      v2.begin(), v2.end(),
+      std::inserter(v_intersection, v_intersection.begin()));
+      // std::back_inserter(v_intersection))); // for vector / list
+
+  for (auto n: v_intersection) {
+    std::cout << "n: " << n << std::endl;
+  }
+
+  std::cout << std::endl;
+  return 0;
+}

current/algorithms/java/Queue.java

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+import java.util.*;
+
+public class Program {
+
+  public static void main(String[] args) {
+
+    var arr = new ArrayList<Integer>();
+
+    arr.add(-4);
+
+    var pq = new PriorityQueue<Integer>();
+    pq.add(1);
+    pq.add(5);
+    pq.add(-3);
+    pq.add(-7);
+
+    System.out.printf("Hello World: %d\n", pq.remove());
+    System.out.printf("Hello World: %d\n", pq.remove());
+    System.out.printf("Hello World: %d\n", pq.remove());
+    System.out.printf("Hello World: %d\n", pq.remove());
+  }
+
+}

current/algorithms/java/Queue2.java

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+import java.util.*;
+
+public class Program2 {
+
+  public record Element(
+      int weight) implements Comparable {
+
+    public int compareTo(Object o) {
+
+      if (!(o instanceof Element)) {
+        throw new IllegalArgumentException("Got invalid class to compare: " + o.getClass());
+      }
+
+      Element e = (Element)o;
+
+      return weight - e.weight;
+    }
+
+    public String toString() {
+      return "Element{weight = %d}".formatted(weight);
+    }
+  }
+
+  public static void main(String[] args) {
+
+    var pq = new PriorityQueue<Element>();
+    pq.add(new Element(1));
+    pq.add(new Element(5));
+    pq.add(new Element(-3));
+    pq.add(new Element(-7));
+
+    System.out.printf("Hello World: %s\n", pq.remove());
+    System.out.printf("Hello World: %s\n", pq.remove());
+    System.out.printf("Hello World: %s\n", pq.remove());
+    System.out.printf("Hello World: %s\n", pq.remove());
+  }
+
+}

current/algorithms/java/README.md

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+# How to run
+
+Run it with :!jbang % in vim.