From 3c0892998c87ee41d18f1a93d98171bb90d39a81 Mon Sep 17 00:00:00 2001
From: Gonzalo Diaz <devel@gon.cl>
Date: Mon, 29 Sep 2025 11:41:38 -0300
Subject: [PATCH] =?UTF-8?q?[Hacker=20Rank]=20Interview=20Preparation=20Kit?=
 =?UTF-8?q?:=20Recursion:=20Davis'=20Staircase.=20Solved=20=E2=9C=85.?=
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---
 docs/hackerrank/warmup/staircase.md           | 67 +++++++++++++++++++
 src/hackerrank/warmup/mod.rs                  |  1 +
 src/hackerrank/warmup/staircase.rs            | 18 +++++
 .../warmup/staircase.testcases.json           |  7 ++
 tests/hackerrank/warmup/mod.rs                |  1 +
 tests/hackerrank/warmup/staircase.rs          | 31 +++++++++
 6 files changed, 125 insertions(+)
 create mode 100644 docs/hackerrank/warmup/staircase.md
 create mode 100644 src/hackerrank/warmup/staircase.rs
 create mode 100644 tests/data/hackerrank/warmup/staircase.testcases.json
 create mode 100644 tests/hackerrank/warmup/staircase.rs

diff --git a/docs/hackerrank/warmup/staircase.md b/docs/hackerrank/warmup/staircase.md
new file mode 100644
index 0000000..201bcc1
--- /dev/null
+++ b/docs/hackerrank/warmup/staircase.md
@@ -0,0 +1,67 @@
+# [Staircase](https://www.hackerrank.com/challenges/staircase)
+
+Difficulty: #easy
+Category: #warmup
+
+Staircase detail
+This is a staircase of size $ n = 4 $:
+
+```text
+   #
+  ##
+ ###
+####
+```
+
+Its base and height are both equal to n. It is drawn using # symbols
+and spaces. The last line is not preceded by any spaces.
+
+Write a program that prints a staircase of size n.
+
+## Function Description
+
+Complete the staircase function in the editor below.
+
+staircase has the following parameter(s):
+
+* int n: an integer
+
+## Print
+
+Print a staircase as described above.
+
+## Input Format
+
+A single integer, , denoting the size of the staircase.
+
+Constraints
+
+$ 0 < n \leq 100 $
+
+## Output Format
+
+Print a staircase of size n using # symbols and spaces.
+
+Note: The last line must have  spaces in it.
+
+## Sample Input
+
+```text
+6
+```
+
+## Sample Output
+
+```text
+     #
+    ##
+   ###
+  ####
+ #####
+######
+```
+
+## Explanation
+
+The staircase is right-aligned, composed of # symbols and spaces,
+and has a height and width of $ n = 6 $.
diff --git a/src/hackerrank/warmup/mod.rs b/src/hackerrank/warmup/mod.rs
index b20dcc1..1c43123 100644
--- a/src/hackerrank/warmup/mod.rs
+++ b/src/hackerrank/warmup/mod.rs
@@ -4,3 +4,4 @@ pub mod compare_triplets;
 pub mod a_very_big_sum;
 pub mod diagonal_difference;
 pub mod plus_minus;
+pub mod staircase;
diff --git a/src/hackerrank/warmup/staircase.rs b/src/hackerrank/warmup/staircase.rs
new file mode 100644
index 0000000..7d09dd9
--- /dev/null
+++ b/src/hackerrank/warmup/staircase.rs
@@ -0,0 +1,18 @@
+// @link Problem definition [[docs/hackerrank/warmup/staircase.md]]
+
+pub fn staircase_string(n: i32) -> String {
+  let mut result: Vec<String> = Vec::new();
+
+  for i in 1..=n {
+    let spaces = " ".repeat((n - i) as usize);
+    let hashes = "#".repeat(i as usize);
+
+    result.push(format!("{}{}", spaces, hashes));
+  }
+
+  result.join("\n")
+}
+
+pub fn staircase(n: i32) {
+  println!("{}", staircase_string(n));
+}
diff --git a/tests/data/hackerrank/warmup/staircase.testcases.json b/tests/data/hackerrank/warmup/staircase.testcases.json
new file mode 100644
index 0000000..cf81f08
--- /dev/null
+++ b/tests/data/hackerrank/warmup/staircase.testcases.json
@@ -0,0 +1,7 @@
+[
+  {
+    "title": "Example",
+    "input": 6,
+    "expected": "     #\n    ##\n   ###\n  ####\n #####\n######"
+  }
+]
diff --git a/tests/hackerrank/warmup/mod.rs b/tests/hackerrank/warmup/mod.rs
index b20dcc1..1c43123 100644
--- a/tests/hackerrank/warmup/mod.rs
+++ b/tests/hackerrank/warmup/mod.rs
@@ -4,3 +4,4 @@ pub mod compare_triplets;
 pub mod a_very_big_sum;
 pub mod diagonal_difference;
 pub mod plus_minus;
+pub mod staircase;
diff --git a/tests/hackerrank/warmup/staircase.rs b/tests/hackerrank/warmup/staircase.rs
new file mode 100644
index 0000000..0e6206d
--- /dev/null
+++ b/tests/hackerrank/warmup/staircase.rs
@@ -0,0 +1,31 @@
+use exercises::hackerrank::warmup::staircase::{staircase, staircase_string};
+use once_cell::sync::Lazy;
+use serde::Deserialize;
+
+use crate::common;
+use common::utils::load_json;
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  #[derive(Debug, Deserialize)]
+  struct AveryBigSumTestCase {
+      input: i32,
+      expected: String
+  }
+
+  static TEST_DATA: Lazy<Vec<AveryBigSumTestCase>> =
+    Lazy::new(|| load_json("tests/data/hackerrank/warmup/staircase.testcases.json"));
+
+  #[test]
+  fn test_staircase() {
+    println!("Testing hackerrank::warmup::staircase::staircase()");
+
+    for test_case in TEST_DATA.iter() {
+      let result = staircase_string(test_case.input);
+      staircase(test_case.input);
+      assert_eq!(result, test_case.expected);
+    }
+  }
+}