Initial checkin

BeefySysLib/perf_tests/fannkuchredux.cpp

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+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include "Common.h"
+
+static void fannkuch(int n, int& sumOut, int& maxflipsOut)
+{
+	int sum = 0;
+	int maxflips = 0;
+	
+	/*int* p = (int*)alloca(sizeof(int)*n);
+	int* q = (int*)alloca(sizeof(int)*n);
+	int* s = (int*)alloca(sizeof(int)*n);*/
+    
+    int* p = new int[n];
+     int* q = new int[n];
+     int* s = new int[n];
+
+	int sign = 1, m = n - 1;
+	for (int i = 0; i < n; i++) { p[i] = i; q[i] = i; s[i] = i; }
+	do
+	{
+		// Copy and flip.
+		int q0 = p[0];                                     // Cache 0th element.
+		if (q0 != 0)
+		{
+			for (int i = 1; i < n; i++) q[i] = p[i];             // Work on a copy.
+			int flips = 1;
+			do
+			{
+				int qq = q[q0];
+				if (qq == 0)
+				{                                // ... until 0th element is 0.
+					sum += sign * flips;
+					if (flips > maxflips) maxflips = flips;   // New maximum?
+					break;
+				}
+				q[q0] = q0;
+				if (q0 >= 3)
+				{
+					int i = 1, j = q0 - 1, t;
+					do { t = q[i]; q[i] = q[j]; q[j] = t; i++; j--; } while (i < j);
+				}
+				q0 = qq; flips++;
+			} while (true);
+		}
+		// Permute.
+		if (sign == 1)
+		{
+			int t = p[1]; p[1] = p[0]; p[0] = t; sign = -1; // Rotate 0<-1.
+		}
+		else
+		{
+			int t = p[1]; p[1] = p[2]; p[2] = t; sign = 1;  // Rotate 0<-1 and 0<-1<-2.
+			for (int i = 2; i < n; i++)
+			{
+				int sx = s[i];
+				if (sx != 0) { s[i] = sx - 1; break; }
+				if (i == m) 
+				{					
+					sumOut = sum;
+					maxflipsOut = maxflips;
+					return;  // Out of permutations.
+				}
+				s[i] = i;
+				// Rotate 0<-...<-i+1.
+				t = p[0]; for (int j = 0; j <= i; j++) { p[j] = p[j + 1]; } p[i + 1] = t;
+			}
+		}
+	} while (true);
+}
+
+
+void FannkuchRedux(int n)
+{	
+	int sum;
+	int maxflips;
+	fannkuch(n, sum, maxflips);
+	Beefy::OutputDebugStrF("%d\nPfannkuchenC(%d) = %d\n", sum, n, maxflips);
+}
+