Rework armstrong num exercise to practice external crates

concepts/external-crates/.meta/config.json

@@ -0,0 +1,7 @@
+{
+    "blurb": "<todo>",
+    "authors": [
+        "misicnenad"
+    ],
+    "contributors": []
+}

concepts/external-crates/about.md

@@ -0,0 +1 @@
+# Packages and Crates

concepts/external-crates/introduction.md

@@ -0,0 +1 @@
+# Introduction

concepts/external-crates/links.json

@@ -0,0 +1 @@
+[]

config.json

@@ -62,8 +62,16 @@
         "name": "Armstrong Numbers",
         "uuid": "4aaa153d-3416-4101-8143-35b068a15451",
         "practices": [
-          "functions",
-          "integers",
+          "external-crates"
+        ],
+        "prerequisites": [],
+        "difficulty": 1
+      },
+      {
+        "slug": "semi-structured-logs",
+        "name": "semi-structured-logs",
+        "uuid": "2b0cd2a4-4767-4494-a239-7b3c0e9b0268",
+        "practices": [
           "enums"
         ],
         "prerequisites": [],

exercises/practice/armstrong-numbers/.meta/example.cairo

@@ -1,39 +1,7 @@
-use core::integer::{u32_overflowing_add};
+use alexandria_math::armstrong_number;
 
 fn is_armstrong_number(num: u32) -> bool {
-    let s = format!("{}", num);
-    let l = s.len();
-    let mut result: Option<u32> = Option::Some(0);
-    let mut i = l;
-    while i != 0 {
-        if let Option::None = result {
-            break;
-        }
-
-        i -= 1;
-
-        // ByteArray.at returns the ASCII representation of the character,
-        // so we need to subtract the position of the decimal '0' in ASCII
-        // (ASCII 48 == 0)
-        let digit: u8 = s.at(i).into().unwrap() - 48;
-
-        result = match u32_overflowing_add(result.unwrap(), pow(digit, l)) {
-            Result::Ok(val) => Option::Some(val),
-            Result::Err(_) => Option::None,
-        };
-    };
-
-    result == Option::Some(num)
-}
-
-fn pow(base: u8, exponent: u32) -> u32 {
-    let mut result: u32 = 1;
-    let mut i = exponent;
-    while i != 0 {
-        result *= base.into(); // cast u8 into u32
-        i -= 1;
-    };
-    result
+    armstrong_number::is_armstrong_number(num.into())
 }
 
 #[cfg(test)]

exercises/practice/armstrong-numbers/Scarb.toml

@@ -2,3 +2,6 @@
 name = "armstrong_numbers"
 version = "0.1.0"
 edition = "2023_11"
+
+[dependencies]
+alexandria_math = { git = "https://github.com/keep-starknet-strange/alexandria.git" }

exercises/practice/semi-structured-logs/.meta/config.json

@@ -0,0 +1,16 @@
+{
+  "authors": [],
+  "files": {
+    "solution": [
+      "src/lib.cairo",
+      "Scarb.toml"
+    ],
+    "test": [
+      "src/tests.cairo"
+    ],
+    "example": [
+      ".meta/example.cairo"
+    ]
+  },
+  "blurb": ""
+}