implemented shop screen after round end

include/game.h

@@ -10,6 +10,7 @@
 #define BG_ID_CARD_SELECTING 1
 #define BG_ID_CARD_PLAYING 2
 #define BG_ID_ROUND_END 3
+#define BG_ID_SHOP 4
 
 enum GameState
 {

include/util.h

@@ -0,0 +1,36 @@
+#ifndef UTIL_H
+#define UTIL_H
+
+static inline int get_digits(int n) // https://stackoverflow.com/questions/1068849/how-do-i-determine-the-number-of-digits-of-an-integer-in-c
+{
+    if (n < 10) return 1;
+    if (n < 100) return 2;
+    if (n < 1000) return 3;
+    if (n < 10000) return 4;
+    if (n < 100000) return 5;
+    if (n < 1000000) return 6;
+    if (n < 10000000) return 7;
+    if (n < 100000000) return 8;
+    if (n < 1000000000) return 9;
+    return 10;
+}
+
+static inline int get_digits_odd(int n)
+{
+    if (n < 100) return 1;
+    if (n < 10000) return 2;
+    if (n < 1000000) return 3;
+    if (n < 100000000) return 4;
+    return 5;
+}
+
+static inline int get_digits_even(int n)
+{
+    if (n < 10) return 1;
+    if (n < 1000) return 2;
+    if (n < 100000) return 3;
+    if (n < 10000000) return 4;
+    return 5;
+}
+
+#endif // UTIL_H