Merge pull request #27 from sir-gon/feature/plus_minus

[Hacker Rank]: Plus Minus solved ✓

Author: sir-gon

docs/hackerrank/warmup/plus_minus.md

@@ -0,0 +1,80 @@
+# [Plus Minus](https://www.hackerrank.com/challenges/plus-minus)
+
+Difficulty: #easy
+Category: #warmup
+
+Given an array of integers, calculate the ratios of its elements
+that are positive, negative, and zero. Print the decimal value of
+each fraction on a new line with 6 places after the decimal.
+
+**Note**: This challenge introduces precision problems.
+The test cases are scaled to six decimal places, though answers
+with absolute error of up to $ 10^{-4} $ are acceptable.
+
+## Example
+
+$ arr = [1, 1, 0, -1, -1] $
+
+There are $ n = 5 $ elements, two positive, two negative and one zero.
+Their ratios are $ 2/5 = 0.400000 $, $ 2/5 = 0.400000 $ and $ 1/5 = 0.200000 $.
+Results are printed as:
+
+```text
+0.400000
+0.400000
+0.200000
+```
+
+## Function Description
+
+Complete the plusMinus function in the editor below.
+plusMinus has the following parameter(s):
+
+- int arr[n]: an array of integers
+
+## Print
+
+Print the ratios of positive, negative and zero values in the array.
+Each value should be printed on a separate line with $ 6 $ digits after
+the decimal. The function should not return a value.
+
+## Input Format
+
+The first line contains an integer, `n`, the size of the array.
+The second line contains `n` space-separated integers that describe `arr[n]`.
+
+## Constraints
+
+$ 0 < n \leq 100 $ \
+$ -100 \leq arr[i] \leq 100 $
+
+## Output Format
+
+**Print** the following  lines, each to  decimals:
+
+1. proportion of positive values
+2. proportion of negative values
+3. proportion of zeros
+
+## Sample Input
+
+```text
+STDIN           Function
+-----           --------
+6               arr[] size n = 6
+-4 3 -9 0 4 1   arr = [-4, 3, -9, 0, 4, 1]
+```
+
+## Sample Output
+
+```text
+0.500000
+0.333333
+0.166667
+```
+
+## Explanation
+
+There are $ 3 $ positive numbers, negative numbers, and $ 1 $ zero in the array.
+The proportions of occurrence are positive: $ 3/6 = 0.500000 $,
+negative: $ 2/6 = 0.333333 $ and zeros: $ 1/6 = 0.166667 $.

src/hackerrank/warmup/mod.rs

@@ -3,3 +3,4 @@ pub mod simple_array_sum;
 pub mod compare_triplets;
 pub mod a_very_big_sum;
 pub mod diagonal_difference;
+pub mod plus_minus;

src/hackerrank/warmup/plus_minus.rs

@@ -0,0 +1,31 @@
+// @link Problem definition [[docs/hackerrank/warmup/solveMeFirst.md]]
+
+pub fn plus_minus_calculate(arr: &[i32]) -> (f64, f64, f64) {
+  let n = arr.len() as f64;
+  let (mut pos, mut neg, mut zero) = (0, 0, 0);
+
+  for &num in arr {
+      if num > 0 {
+          pos += 1;
+      } else if num < 0 {
+          neg += 1;
+      } else {
+          zero += 1;
+      }
+  }
+
+  (pos as f64 / n, neg as f64 / n, zero as f64 / n)
+}
+
+pub fn plus_minus_calculate_string(arr: &[i32]) -> (String, String, String) {
+  let (pos, neg, zero) = plus_minus_calculate(arr);
+  (format!("{:.6}", pos, ), format!("{:.6}", neg), format!("{:.6}", zero))
+}
+
+pub fn plus_minus(arr: &[i32]) {
+  let (pos, neg, zero) = plus_minus_calculate_string(arr);
+
+  println!("{}", pos);
+  println!("{}", neg);
+  println!("{}", zero);
+}

tests/data/hackerrank/warmup/plus_minus.testcases.json

@@ -0,0 +1,7 @@
+[
+  {
+    "title": "test case 0",
+    "input": [-4, 3, -9, 0, 4, 1],
+    "expected": ["0.500000", "0.333333", "0.166667"]
+  }
+]

tests/hackerrank/warmup/mod.rs

@@ -3,3 +3,4 @@ pub mod simple_array_sum;
 pub mod compare_triplets;
 pub mod a_very_big_sum;
 pub mod diagonal_difference;
+pub mod plus_minus;

tests/hackerrank/warmup/plus_minus.rs

@@ -0,0 +1,39 @@
+use serde::Deserialize;
+use once_cell::sync::Lazy;
+
+use exercises::hackerrank::warmup::plus_minus::plus_minus;
+use exercises::hackerrank::warmup::plus_minus::plus_minus_calculate_string;
+use crate::common::utils::load_json;
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  #[derive(Debug, Deserialize)]
+  struct PlusMinusTestCase {
+    title: String,
+    input: Vec<i32>,
+    expected: Vec<String>,
+  }
+
+  static TEST_DATA: Lazy<Vec<PlusMinusTestCase>> =
+      Lazy::new(|| load_json("tests/data/hackerrank/warmup/plus_minus.testcases.json"));
+
+  #[test]
+  fn test_plus_minus() {
+    for test_case in TEST_DATA.iter() {
+      println!("Testing hackerrank::warmup::plus_minus::plus_minus() : {:?}", test_case.title);
+
+      let expected: (_, _, _) = (
+        test_case.expected[0].clone(),
+        test_case.expected[1].clone(),
+        test_case.expected[2].clone()
+      );
+      let result = plus_minus_calculate_string(test_case.input.as_slice());
+      assert_eq!(result, expected);
+
+      // call printer for coverage
+      plus_minus(test_case.input.as_slice());
+    }
+  }
+}