Thu Jul 2 19:11:01 2020 UTC ()

cgram(6): use standard cursor keys, use standard shuffle algorithm

The previous shuffle algorithm asked for 100 random numbers, on average.
The new algorithm asks exactly for 26 random numbers.

Curses predefines numeric constants for keys, and there is no apparent
reason not to use these standard keys for cursor movement.


(rillig)

diff -r1.1 -r1.2 src/games/cgram/cgram.c

--- src/games/cgram/cgram.c 2013/08/04 05:42:47	1.1
+++ src/games/cgram/cgram.c 2020/07/02 19:11:01	1.2

 @@ -110,36 +110,33 @@ static void readquote(void) {
 	    buf2[j++] = buf[i];
+	 }
+      }
       buf2[j] = 0;
       stringarray_add(&lines, buf2);
       stringarray_add(&sollines, buf2);
+   }
    pclose(f);
+}
 static void encode(void) {
    int used[26];
    for (int i=0; i<26; i++) used[i] = 0;
    int key[26];
-   int keypos=0;
+   for (int i=0; i<26; i++) key[i] = i;
-   while (keypos < 26) {
+   for (int i=26; i>1; i--) {
-      int c = random()%26;
+      int c = random() % i;
-      if (used[c]) continue;
+      int t = key[i-1];
-      key[keypos++] = c;
+      key[i-1] = key[c];
-      used[c] = 1;
+      key[c] = t;
+   }
    for (int y=0; y<lines.num; y++) {
       for (unsigned x=0; lines.v[y][x]; x++) {
 	 if (islower((unsigned char)lines.v[y][x])) {
 	    int q = lines.v[y][x]-'a';
 	    lines.v[y][x] = 'a'+key[q];
+	 }
 	 if (isupper((unsigned char)lines.v[y][x])) {
 	    int q = lines.v[y][x]-'A';
 	    lines.v[y][x] = 'A'+key[q];
+	 }
+      }
 @@ -234,64 +231,70 @@ static void opencurses(void) {
 static void closecurses(void) {
    endwin();
+}
 ////////////////////////////////////////////////////////////
 static void loop(void) {
    bool done=false;
    while (!done) {
       redraw();
       int ch = getch();
       switch (ch) {
        case 1: /* ^A */
        case KEY_BEG:
 	curx=0;
 	break;
        case 2: /* ^B */
        case KEY_LEFT:
 	if (curx > 0) {
 	   curx--;
+	}
 	else if (cury > 0) {
 	   cury--;
 	   curx = strlen(lines.v[cury]);
+	}
 	break;
        case 5: /* ^E */
        case KEY_END:
 	curx = strlen(lines.v[cury]);
 	break;
        case 6: /* ^F */
        case KEY_RIGHT:
 	if (curx < strlen(lines.v[cury])) {
 	   curx++;
+	}
 	else if (cury < lines.num - 1) {
 	   cury++;
 	   curx = 0;
+	}
 	break;
        case 12: /* ^L */
 	clear();
 	break;
        case 14: /* ^N */
        case KEY_DOWN:
 	if (cury < lines.num-1) {
 	   cury++;
+	}
 	if (curx > strlen(lines.v[cury])) {
 	   curx =  strlen(lines.v[cury]);
+	}
 	if (scrolldown < cury - (LINES-2)) {
 	   scrolldown = cury - (LINES-2);
+	}
 	break;
        case 16: /* ^P */
        case KEY_UP:
 	if (cury > 0) {
 	   cury--;
+	}
 	if (curx > strlen(lines.v[cury])) {
 	   curx = strlen(lines.v[cury]);
+	}
 	if (scrolldown > cury) {
 	   scrolldown = cury;
+	}
 	break;
        case '*':
 	hinting = !hinting;
 	break;
 @@ -325,20 +328,21 @@ static void loop(void) {
+   }
+}
 ////////////////////////////////////////////////////////////
 int main(void) {
    stringarray_init(&lines);
    stringarray_init(&sollines);
    srandom(time(NULL));
    readquote();
    encode();
    opencurses();
    keypad(stdscr, TRUE);
    loop();
    closecurses();
    stringarray_cleanup(&sollines);
    stringarray_cleanup(&lines);
    return 0;
+}