added test for quick select

tests/quick_select_test.cc

@@ -0,0 +1,38 @@
+/*
+Test for the Quick select algorithm
+
+Copyright 2024 Ahmet Inan <inan@aicodix.de>
+*/
+
+#include <random>
+#include <cassert>
+#include <iostream>
+#include <algorithm>
+#include <functional>
+#include "quick_select.hh"
+
+int main()
+{
+	const int MAX_N = 1 << 16;
+	unsigned seed = 42;
+	if (1) {
+		std::random_device rd;
+		seed = rd();
+	}
+	typedef std::default_random_engine generator;
+	typedef std::uniform_int_distribution<int> distribution;
+	auto rand = std::bind(distribution(1, MAX_N), generator(seed));
+	int a[MAX_N], b[MAX_N];
+	for (int loop = 0; loop < 10000; ++loop) {
+		int size = rand();
+		for (int i = 0; i < size; ++i)
+			a[i] = b[i] = rand();
+		int k = rand() % size;
+		std::nth_element(a, a+k, a+size);
+		int v = DSP::quick_select(b, k, size);
+		assert(v == a[k]);
+	}
+	std::cerr << "Quick select algorithm test passed!" << std::endl;
+	return 0;
+}
+