Implement fizzbuzz in cairo

examples/cairo/scripts/fizzbuzz/.tool-versions

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+scarb 2.11.2

examples/cairo/scripts/fizzbuzz/Scarb.lock

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+# Code generated by scarb DO NOT EDIT.
+version = 1
+
+[[package]]
+name = "fizzbuzz"
+version = "0.1.0"

examples/cairo/scripts/fizzbuzz/Scarb.toml

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+[package]
+name = "fizzbuzz"
+version = "0.1.0"
+edition = "2024_07"
+
+# See more keys and their definitions at https://docs.swmansion.com/scarb/docs/reference/manifest.html
+
+[dependencies]
+
+[dev-dependencies]
+cairo_test = "2.11.2"

examples/cairo/scripts/fizzbuzz/src/fizz_buzz.cairo

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+use core::array::ArrayTrait;
+use crate::utils::number_converter::u32_to_felt252;
+
+/// Implementation of the classic FizzBuzz problem.
+/// Takes a number n and returns an array of strings from 1 to n, where:
+/// - Numbers divisible by 3 are replaced with "Fizz"
+/// - Numbers divisible by 5 are replaced with "Buzz"
+/// - Numbers divisible by both 3 and 5 are replaced with "FizzBuzz"
+/// - Otherwise, the number itself is included as a string
+pub fn fizzbuzz(n: u32) -> Array<felt252> {
+    let mut result: Array<felt252> = ArrayTrait::new();
+    let mut i: u32 = 1;
+
+    loop {
+        if i % 3 == 0 && i % 5 == 0 {
+            result.append('FizzBuzz');
+        } else if i % 3 == 0 {
+            result.append('Fizz');
+        } else if i % 5 == 0 {
+            result.append('Buzz');
+        } else {
+            // Convert integer to string representation using our utility function
+            result.append(u32_to_felt252(i));
+        }
+
+        i += 1;
+        if i > n {
+            break;
+        }
+    }
+    result
+}

examples/cairo/scripts/fizzbuzz/src/lib.cairo

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+pub mod fizz_buzz;
+pub mod utils {
+    pub mod number_converter;
+}

examples/cairo/scripts/fizzbuzz/src/utils/number_converter.cairo

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+/// Converts a u32 integer to its string representation as felt252.
+/// This function works for any u32 value, not just small numbers.
+pub fn u32_to_felt252(mut num: u32) -> felt252 {
+    // Handle 0 separately
+    if num == 0 {
+        return '0';
+    }
+
+    // For single-digit numbers (1-9), return the ASCII directly
+    if num < 10 {
+        return num.into() + '0';
+    }
+
+    // For multi-digit numbers, build the string from right to left
+    let mut reversed_digits: Array<felt252> = ArrayTrait::new();
+
+    loop {
+        let digit = (num % 10).into() + '0';
+        reversed_digits.append(digit);
+        num /= 10;
+
+        if num == 0 {
+            break;
+        }
+    }
+
+    // Convert the array of digits to a single felt252 string
+    let mut result: felt252 = 0;
+
+    // Start from the end (least significant digit) and build the number
+    let len = reversed_digits.len();
+    let mut i: usize = 0;
+    while i != len {
+        let index = len - i - 1;
+        let digit = *reversed_digits.at(index);
+        result = result * 256 + digit; // Shift left by 8 bits (1 byte) and add the next digit
+        i += 1;
+    }
+
+    result
+}

examples/cairo/scripts/fizzbuzz/tests/test_fizzbuzz.cairo

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+use fizzbuzz::fizz_buzz;
+
+#[test]
+fn fizzbuzz_test_n3() {
+    let mut result = fizz_buzz::fizzbuzz(3);
+    assert(*result[0] == '1', 'First element should be 1');
+    assert(*result[1] == '2', 'Second element should be 2');
+    assert(*result[2] == 'Fizz', 'Third element should be Fizz');
+}
+
+#[test]
+fn fizzbuzz_test_n5() {
+    let result = fizz_buzz::fizzbuzz(5);
+    assert(*result[0] == '1', 'First element should be 1');
+    assert(*result[1] == '2', 'Second element should be 2');
+    assert(*result[2] == 'Fizz', 'Third element should be Fizz');
+    assert(*result[3] == '4', 'Fourth element should be 4');
+    assert(*result[4] == 'Buzz', 'Fifth element should be Buzz');
+}
+
+#[test]
+fn fizzbuzz_test_n15() {
+    let result = fizz_buzz::fizzbuzz(15);
+    assert(*result[0] == '1', 'Element at index 0');
+    assert(*result[1] == '2', 'Element at index 1');
+    assert(*result[2] == 'Fizz', 'Element at index 2');
+    assert(*result[3] == '4', 'Element at index 3');
+    assert(*result[4] == 'Buzz', 'Element at index 4');
+    assert(*result[5] == 'Fizz', 'Element at index 5');
+    assert(*result[6] == '7', 'Element at index 6');
+    assert(*result[7] == '8', 'Element at index 7');
+    assert(*result[8] == 'Fizz', 'Element at index 8');
+    assert(*result[9] == 'Buzz', 'Element at index 9');
+    assert(*result[10] == '11', 'Element at index 10');
+    assert(*result[11] == 'Fizz', 'Element at index 11');
+    assert(*result[12] == '13', 'Element at index 12');
+    assert(*result[13] == '14', 'Element at index 13');
+    assert(*result[14] == 'FizzBuzz', 'Element at index 14');
+}