Add problem 2057: Smallest Index With Equal Value

src/lib.rs

@@ -1412,6 +1412,7 @@ pub mod problem_2042_check_if_numbers_are_ascending_in_a_sentence;
 pub mod problem_2043_simple_bank_system;
 pub mod problem_2047_number_of_valid_words_in_a_sentence;
 pub mod problem_2053_kth_distinct_string_in_an_array;
+pub mod problem_2057_smallest_index_with_equal_value;
 
 #[cfg(test)]
 mod test_utilities;

src/problem_2057_smallest_index_with_equal_value/iterative.rs

@@ -0,0 +1,39 @@
+pub struct Solution;
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl Solution {
+    pub fn smallest_equal(nums: Vec<i32>) -> i32 {
+        let mut i_mod_10 = 0;
+
+        for (i, num) in (0..).zip(nums) {
+            if i_mod_10 == num {
+                return i;
+            }
+
+            if i_mod_10 == 9 {
+                i_mod_10 = 0;
+            } else {
+                i_mod_10 += 1;
+            }
+        }
+
+        -1
+    }
+}
+
+// ------------------------------------------------------ snip ------------------------------------------------------ //
+
+impl super::Solution for Solution {
+    fn smallest_equal(nums: Vec<i32>) -> i32 {
+        Self::smallest_equal(nums)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}

src/problem_2057_smallest_index_with_equal_value/mod.rs

@@ -0,0 +1,22 @@
+pub mod iterative;
+
+pub trait Solution {
+    fn smallest_equal(nums: Vec<i32>) -> i32;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [
+            (&[0, 1, 2] as &[_], 0),
+            (&[4, 3, 2, 1], 2),
+            (&[1, 2, 3, 4, 5, 6, 7, 8, 9, 0], -1),
+        ];
+
+        for (nums, expected) in test_cases {
+            assert_eq!(S::smallest_equal(nums.to_vec()), expected);
+        }
+    }
+}