From 58915c4d5d6ee0ccd0862e223cd81e0cbbdf77ca Mon Sep 17 00:00:00 2001
From: Dnomd343 <i@343.re>
Date: Fri, 6 Jan 2023 19:14:11 +0800
Subject: [PATCH] feat: short code from string

---
 klotski/main.cc       |  1 +
 klotski/short_code.cc | 32 +++++++++++++++++++++++++++++++-
 klotski/short_code.h  | 32 ++++++++++++++++++++------------
 3 files changed, 52 insertions(+), 13 deletions(-)

diff --git a/klotski/main.cc b/klotski/main.cc
index 42aa8c0..b0fe356 100644
--- a/klotski/main.cc
+++ b/klotski/main.cc
@@ -63,6 +63,7 @@ int main() {
 
 
     std::cout << ShortCode::code_to_string(14323231) << std::endl;
+    std::cout << ShortCode::code_from_string("EP4HZ") << std::endl;
 
     return 0;
 }
diff --git a/klotski/short_code.cc b/klotski/short_code.cc
index a4e61dc..a97ba91 100644
--- a/klotski/short_code.cc
+++ b/klotski/short_code.cc
@@ -13,7 +13,7 @@ bool ShortCode::check(uint32_t short_code) {
     return short_code < ShortCode::SHORT_CODE_LIMIT; // 0 ~ (SHORT_CODE_LIMIT - 1)
 }
 
-std::string ShortCode::code_to_string(uint32_t short_code) {
+std::string ShortCode::code_to_string(uint32_t short_code) { // encode as 5-bits string
     if (!ShortCode::check(short_code)) {
         throw std::range_error("short code out of range");
     }
@@ -26,6 +26,36 @@ std::string ShortCode::code_to_string(uint32_t short_code) {
     return result;
 }
 
+uint32_t ShortCode::code_from_string(const std::string &short_code) { // 5-bits string decode as number
+    if (short_code.length() != 5) {
+        throw std::runtime_error("invalid short code");
+    }
+    uint32_t result = 0;
+    for (auto bit : short_code) {
+        result *= 32;
+        if (bit >= '1' && bit <= '9') { // 1 ~ 9
+            result += bit - 49;
+            continue;
+        }
+        if (bit >= 'a' && bit <= 'z') { // a ~ z
+            bit -= ('a' - 'A'); // convert to A ~ Z
+        }
+        if (bit >= 'A' && bit <= 'Z') { // A ~ Z
+            bit = SHORT_CODE_TABLE_REV[bit - 65]; // table convert
+            if (bit == 0) {
+                throw std::runtime_error("invalid short code");
+            }
+            result += bit;
+        } else {
+            throw std::runtime_error("invalid short code");
+        }
+    }
+    if (!ShortCode::check(result)) {
+        throw std::range_error("short code out of range");
+    }
+    return result;
+}
+
 void ShortCode::speed_up(enum Mode mode) { // speed up handle short code
     switch (mode) {
         case Mode::NORMAL: // speed up into normal mode
diff --git a/klotski/short_code.h b/klotski/short_code.h
index d5715fa..1cd6ca9 100644
--- a/klotski/short_code.h
+++ b/klotski/short_code.h
@@ -11,20 +11,28 @@ const char SHORT_CODE_TABLE[32] = {
     'N', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z',
 };
 
-// 1 -> 48
-// ...
-// 9 -> 57
-// A -> 65
+const char SHORT_CODE_TABLE_REV[26] = {
+//  00  01  02  03  04  05  06  07  08  09
+     9, 10, 11, 12, 13, 14, 15, 16,  0, 17,
+//  10  11  12  13  14  15  16  17  18  19
+    18,  0, 19, 20,  0, 21, 22, 23, 24, 25,
+//  20  21  22  23  24  25
+    26, 27, 28, 29, 30, 31,
+};
+
+// 00: 1 -> 48
 // ...
-// H -> 72
-// J -> 74
+// 08: 9 -> 57
+// 09: A -> 65 (00)
 // ...
-// K -> 75
-// M -> 77
-// N -> 78
-// P -> 80
+// 16: H -> 72 (07)
+// 17: J -> 74 (09)
+// 18: K -> 75 (10)
+// 19: M -> 77 (12)
+// 20: N -> 78 (13)
+// 21: P -> 80 (15)
 // ...
-// Z -> 90
+// 31: Z -> 90 (25)
 
 class ShortCode {
 public:
@@ -39,7 +47,7 @@ public:
     uint64_t unzip_short_code(uint32_t short_code);
 
     static std::string code_to_string(uint32_t short_code);
-//    static uint32_t code_from_string(const std::string &short_code);
+    static uint32_t code_from_string(const std::string &short_code);
 
 private:
     static const uint32_t SHORT_CODE_LIMIT = 29334498;