Initial data commit

Task/Priority-queue/Zig/priority-queue-1.zig

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+const std = @import("std");
+const PriorityQueue = std.PriorityQueue;
+const Allocator = std.mem.Allocator;
+const testing = std.testing;
+
+/// wrapper for the task - stores task priority
+/// along with the task name
+const Task = struct {
+    const Self = @This();
+
+    priority: i32,
+    name: []const u8,
+
+    pub fn init(priority: i32, name: []const u8) Self {
+        return Self{
+            .priority = priority,
+            .name = name,
+        };
+    }
+};
+
+/// Simple wrapper for the comparator function.
+/// Each comparator function has the following signature:
+///
+/// fn(T, T) bool
+const Comparator = struct {
+    fn maxCompare(a: Task, b: Task) bool {
+        return a.priority > b.priority;
+    }
+
+    fn minCompare(a: Task, b: Task) bool {
+        return a.priority < b.priority;
+    }
+};
+
+test "priority queue (max heap)" {
+    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    defer arena.deinit();
+    var allocator = &arena.allocator;
+
+    var pq = PriorityQueue(Task).init(allocator, Comparator.maxCompare);
+    defer pq.deinit();
+
+    try pq.add(Task.init(3, "Clear drains"));
+    try pq.add(Task.init(4, "Feed Cat"));
+    try pq.add(Task.init(5, "Make tea"));
+    try pq.add(Task.init(1, "Solve RC tasks"));
+    try pq.add(Task.init(2, "Tax returns"));
+    testing.expectEqual(pq.count(), 5);
+
+    std.debug.print("\n", .{});
+
+    // execute the tasks in decreasing order of priority
+    while (pq.count() != 0) {
+        const task = pq.remove();
+        std.debug.print("Executing:  {} (priority {})\n", .{ task.name, task.priority });
+    }
+    std.debug.print("\n", .{});
+}
+
+test "priority queue (min heap)" {
+    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    defer arena.deinit();
+    var allocator = &arena.allocator;
+
+    var pq = PriorityQueue(Task).init(allocator, Comparator.minCompare);
+    defer pq.deinit();
+
+    try pq.add(Task.init(3, "Clear drains"));
+    try pq.add(Task.init(4, "Feed Cat"));
+    try pq.add(Task.init(5, "Make tea"));
+    try pq.add(Task.init(1, "Solve RC tasks"));
+    try pq.add(Task.init(2, "Tax returns"));
+    testing.expectEqual(pq.count(), 5);
+
+    std.debug.print("\n", .{});
+
+    // execute the tasks in increasing order of priority
+    while (pq.count() != 0) {
+        const task = pq.remove();
+        std.debug.print("Executing:  {} (priority {})\n", .{ task.name, task.priority });
+    }
+    std.debug.print("\n", .{});
+}