Data commit

Task/Penneys-game/C/penneys-game.c

@@ -0,0 +1,121 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#define SEQLEN 3
+
+int getseq(char *s)
+{
+    int r = 0;
+    int i = 1 << (SEQLEN - 1);
+
+    while (*s && i) {
+        switch (*s++) {
+            case 'H':
+            case 'h':
+                r |= i;
+                break;
+            case 'T':
+            case 't':
+                /* 0 indicates tails, this is 0, so do nothing */
+                break;
+            default:
+                return -1;
+        }
+        i >>= 1;
+    }
+
+    return r;
+}
+
+void printseq(int seq)
+{
+    int i;
+    for (i = SEQLEN - 1; i >= 0; --i)
+        printf("%c", seq & (1 << i) ? 'h' : 't');
+}
+
+int getuser(void)
+{
+    int user;
+    char s[SEQLEN + 1];
+
+    printf("Enter your sequence of %d (h/t): ", SEQLEN);
+    while (1) {
+        /* This needs to be manually changed if SEQLEN is changed */
+        if (scanf("%3s", s) != 1) exit(1);
+        if ((user = getseq(s)) != -1) return user;
+        printf("Please enter only h/t characters: ");
+    }
+}
+
+int getai(int user)
+{
+    int ai;
+
+    printf("Computers sequence of %d is: ", SEQLEN);
+    /* The ai's perfect choice will only be perfect for SEQLEN == 3 */
+    if (user == -1)
+        ai = rand() & (1 << SEQLEN) - 1;
+    else
+        ai = (user >> 1) | ((~user << 1) & (1 << SEQLEN - 1));
+
+    printseq(ai);
+    printf("\n");
+    return ai;
+}
+
+int rungame(int user, int ai)
+{
+    /* Generate first SEQLEN flips. We only need to store the last SEQLEN
+     * tosses at any one time. */
+    int last3 = rand() & (1 << SEQLEN) - 1;
+
+    printf("Tossed sequence: ");
+    printseq(last3);
+    while (1) {
+        if (user == last3) {
+            printf("\nUser wins!\n");
+            return 1;
+        }
+
+        if (ai == last3) {
+            printf("\nAi wins!\n");
+            return 0;
+        }
+
+        last3 = ((last3 << 1) & (1 << SEQLEN) - 2) | (rand() & 1);
+        printf("%c", last3 & 1 ? 'h' : 't');
+    }
+}
+
+int main(void)
+{
+    srand(time(NULL));
+    int playerwins = 0;
+    int totalgames = 0;
+
+    /* Just use ctrl-c for exit */
+    while (1) {
+        int user = -1;
+        int ai   = -1;
+
+        printf("\n");
+        if (rand() & 1) {
+            ai   = getai(user);
+            user = getuser();
+        }
+        else {
+            user = getuser();
+            ai   = getai(user);
+        }
+
+        playerwins += rungame(user, ai);
+        totalgames++;
+
+        printf("You have won %d out of %d games\n", playerwins, totalgames);
+        printf("=================================\n");
+    }
+
+    return 0;
+}