diff --git a/src/lib.rs b/src/lib.rs
index 59a099a..f6d386a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -415,6 +415,7 @@ pub mod problem_0841_keys_and_rooms;
 pub mod problem_0844_backspace_string_compare;
 pub mod problem_0845_longest_mountain_in_array;
 pub mod problem_0846_hand_of_straights;
+pub mod problem_0851_loud_and_rich;
 pub mod problem_0859_buddy_strings;
 pub mod problem_0917_reverse_only_letters;
 pub mod problem_2348_number_of_zero_filled_subarrays;
diff --git a/src/problem_0851_loud_and_rich/dfs.rs b/src/problem_0851_loud_and_rich/dfs.rs
new file mode 100644
index 0000000..f2556de
--- /dev/null
+++ b/src/problem_0851_loud_and_rich/dfs.rs
@@ -0,0 +1,56 @@
+pub struct Solution;
+
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn loud_and_rich(richer: Vec<Vec<i32>>, quiet: Vec<i32>) -> Vec<i32> {
+        fn helper(
+            person: usize,
+            richer_map: &HashMap<usize, Vec<usize>>,
+            quiet: &[i32],
+            result: &mut [i32],
+        ) -> (i32, usize) {
+            if result[person] != -1 {
+                let person = result[person] as usize;
+                return (quiet[person], person);
+            }
+
+            let mut min = (quiet[person], person);
+            if let Some(richer) = richer_map.get(&person) {
+                for &person in richer {
+                    let child = helper(person, richer_map, quiet, result);
+                    min = min.min(child);
+                }
+            }
+            result[person] = min.1 as i32;
+            min
+        }
+
+        let mut result = vec![-1; quiet.len()];
+        let mut richer_map = HashMap::<usize, Vec<usize>>::with_capacity(quiet.len());
+        for richer in richer {
+            richer_map
+                .entry(richer[1] as usize)
+                .and_modify(|x| x.push(richer[0] as usize))
+                .or_insert_with(|| vec![richer[0] as usize]);
+        }
+        for person in 0..quiet.len() {
+            helper(person, &richer_map, &quiet, &mut result);
+        }
+        result
+    }
+}
+
+impl super::Solution for Solution {
+    fn loud_and_rich(richer: Vec<Vec<i32>>, quiet: Vec<i32>) -> Vec<i32> {
+        Self::loud_and_rich(richer, quiet)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_solution() {
+        super::super::tests::run::<super::Solution>();
+    }
+}
diff --git a/src/problem_0851_loud_and_rich/mod.rs b/src/problem_0851_loud_and_rich/mod.rs
new file mode 100644
index 0000000..d36d586
--- /dev/null
+++ b/src/problem_0851_loud_and_rich/mod.rs
@@ -0,0 +1,27 @@
+pub mod dfs;
+
+pub trait Solution {
+    fn loud_and_rich(richer: Vec<Vec<i32>>, quiet: Vec<i32>) -> Vec<i32>;
+}
+
+#[cfg(test)]
+mod tests {
+    use super::Solution;
+
+    pub fn run<S: Solution>() {
+        let test_cases = [(
+            (
+                &[[1, 0], [2, 1], [3, 1], [3, 7], [4, 3], [5, 3], [6, 3]] as &[_],
+                &[3, 2, 5, 4, 6, 1, 7, 0] as &[_],
+            ),
+            &[5, 5, 2, 5, 4, 5, 6, 7] as &[_],
+        )];
+
+        for ((richer, quiet), expected) in test_cases {
+            assert_eq!(
+                S::loud_and_rich(richer.iter().map(Vec::from).collect(), quiet.to_vec()),
+                expected
+            );
+        }
+    }
+}