Data commit

Task/Perfect-shuffle/C/perfect-shuffle.c

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+/* ===> INCLUDES <============================================================*/
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+/* ===> CONSTANTS <===========================================================*/
+#define N_DECKS 7
+const int kDecks[N_DECKS] = { 8, 24, 52, 100, 1020, 1024, 10000 };
+
+/* ===> FUNCTION PROTOTYPES <=================================================*/
+int CreateDeck( int **deck, int nCards );
+void InitDeck( int *deck, int nCards );
+int DuplicateDeck( int **dest, const int *orig, int nCards );
+int InitedDeck( int *deck, int nCards );
+int ShuffleDeck( int *deck, int nCards );
+void FreeDeck( int **deck );
+
+/* ===> FUNCTION DEFINITIONS <================================================*/
+
+int main() {
+    int i, nCards, nShuffles;
+    int *deck = NULL;
+
+    for( i=0; i<N_DECKS; ++i ) {
+        nCards = kDecks[i];
+
+        if( !CreateDeck(&deck,nCards) ) {
+            fprintf( stderr, "Error: malloc() failed!\n" );
+            return 1;
+        }
+
+        InitDeck( deck, nCards );
+        nShuffles = 0;
+
+        do {
+            ShuffleDeck( deck, nCards );
+            ++nShuffles;
+        } while( !InitedDeck(deck,nCards) );
+
+        printf( "Cards count: %d, shuffles required: %d.\n", nCards, nShuffles );
+
+        FreeDeck( &deck );
+    }
+
+    return 0;
+}
+
+int CreateDeck( int **deck, int nCards ) {
+    int *tmp = NULL;
+
+    if( deck != NULL )
+        tmp = malloc( nCards*sizeof(*tmp) );
+
+    return tmp!=NULL ? (*deck=tmp)!=NULL : 0; /* (?success) (:failure) */
+}
+
+void InitDeck( int *deck, int nCards ) {
+    if( deck != NULL ) {
+        int i;
+
+        for( i=0; i<nCards; ++i )
+            deck[i] = i;
+    }
+}
+
+int DuplicateDeck( int **dest, const int *orig, int nCards ) {
+    if( orig != NULL && CreateDeck(dest,nCards) ) {
+        memcpy( *dest, orig, nCards*sizeof(*orig) );
+        return 1; /* success */
+    }
+    else {
+        return 0; /* failure */
+    }
+}
+
+int InitedDeck( int *deck, int nCards ) {
+    int i;
+
+    for( i=0; i<nCards; ++i )
+        if( deck[i] != i )
+            return 0; /* not inited */
+
+    return 1; /* inited */
+}
+
+int ShuffleDeck( int *deck, int nCards ) {
+    int *copy = NULL;
+
+    if( DuplicateDeck(&copy,deck,nCards) ) {
+        int i, j;
+
+        for( i=j=0; i<nCards/2; ++i, j+=2 ) {
+            deck[j] = copy[i];
+            deck[j+1] = copy[i+nCards/2];
+        }
+
+        FreeDeck( &copy );
+        return 1; /* success */
+    }
+    else {
+        return 0; /* failure */
+    }
+}
+
+void FreeDeck( int **deck ) {
+    if( *deck != NULL ) {
+        free( *deck );
+        *deck = NULL;
+    }
+}