seed everything with the same values

counting_sort/Main.cpp

@@ -9,6 +9,13 @@ int intKey(const int& i) {
     return i;
 }
 
+static unsigned long seed = 0;
+
+int randomInt() {
+    seed = (seed * 0x5DEECE66DL + 0xBL) & 0xFFFFFFFFFFFF;
+    return static_cast<int>(seed >> 17);
+}
+
 template<typename T>
 T* countingSort(const T* in, int size, int max, int (*key)(const T&)) {
     max++;
@@ -35,8 +42,9 @@ void cacheTest() {
         printf("Cache Test with size = %9d | ", size);
         constexpr int max = 500;
         int* a = new int[size];
+        seed = 0;
         for(int i = 0; i < size; i++) {
-            a[i] = rand() % max;
+            a[i] = randomInt() % max;
         }
         long time = -getNanos();
         int* b = countingSort(a, size, max - 1, intKey);
@@ -62,8 +70,9 @@ void structTest() {
         printf("Struct Test with size = %9d | ", size);
         constexpr int max = 500;
         A* a = new A[size];
+        seed = 0;
         for(int i = 0; i < size; i++) {
-            a[i].key = rand() % max;
+            a[i].key = randomInt() % max;
         }
         long time = -getNanos();
         A* b = countingSort(a, size, max - 1, aKey);
@@ -84,8 +93,9 @@ void pointerTest() {
         printf("Pointer Test with size = %9d | ", size);
         constexpr int max = 500;
         int** a = new int*[size];
+        seed = 0;
         for(int i = 0; i < size; i++) {
-            a[i] = new int(rand() % max);
+            a[i] = new int(randomInt() % max);
         }
         long time = -getNanos();
         int** b = countingSort<int*>(a, size, max - 1, pointerKey);