problems(rs): add “2101. Detonate the Maximum Bombs”

Signed-off-by: Matej Focko <mfocko@redhat.com>

problems/rs/detonate-the-maximum-bombs.rs

@@ -0,0 +1,118 @@
+use std::collections::{HashMap, HashSet, VecDeque};
+
+fn distance(a: (i64, i64), b: (i64, i64)) -> i64 {
+    let (x1, y1) = a;
+    let (x2, y2) = b;
+
+    (x1 - x2).pow(2) + (y1 - y2).pow(2)
+}
+
+struct Graph {
+    edges: HashMap<usize, HashSet<usize>>,
+}
+
+impl Graph {
+    fn new(bombs: &[Vec<i32>]) -> Self {
+        let mut edges = HashMap::new();
+
+        for (i, bomb) in bombs.iter().enumerate() {
+            edges.insert(i, HashSet::new());
+            let neighbours = edges.get_mut(&i).unwrap();
+
+            let (x, y, r) = (bomb[0], bomb[1], bomb[2]);
+            let rr = (r as i64).pow(2);
+
+            for j in 0..bombs.len() {
+                if i == j {
+                    continue;
+                }
+
+                let (x1, y1) = (bombs[j][0], bombs[j][1]);
+
+                if distance((x as i64, y as i64), (x1 as i64, y1 as i64)) <= rr {
+                    neighbours.insert(j);
+                }
+            }
+        }
+
+        Self { edges }
+    }
+
+    fn bfs(&self, mut visited: Vec<bool>, u0: usize) -> i32 {
+        let mut found = 0;
+
+        let mut q = VecDeque::new();
+        q.push_back(u0);
+        visited[u0] = true;
+
+        while let Some(u) = q.pop_front() {
+            found += 1;
+
+            for &v in self.edges.get(&u).unwrap_or(&HashSet::new()) {
+                if !visited[v] {
+                    q.push_back(v);
+                    visited[v] = true;
+                }
+            }
+        }
+
+        found
+    }
+}
+
+struct Solution {}
+impl Solution {
+    pub fn maximum_detonation(bombs: Vec<Vec<i32>>) -> i32 {
+        let graph = Graph::new(&bombs);
+        let visited = vec![false; bombs.len()];
+        (0..bombs.len())
+            .map(|u| graph.bfs(visited.clone(), u))
+            .max()
+            .unwrap_or(0)
+    }
+}
+
+fn main() {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn example_1() {
+        assert_eq!(
+            Solution::maximum_detonation(vec![vec![2, 1, 3], vec![6, 1, 4]]),
+            2
+        );
+    }
+
+    #[test]
+    fn example_2() {
+        assert_eq!(
+            Solution::maximum_detonation(vec![vec![1, 1, 5], vec![10, 10, 5]]),
+            1
+        );
+    }
+
+    #[test]
+    fn example_3() {
+        assert_eq!(
+            Solution::maximum_detonation(vec![
+                vec![1, 2, 3],
+                vec![2, 3, 1],
+                vec![3, 4, 2],
+                vec![4, 5, 3],
+                vec![5, 6, 4]
+            ]),
+            5
+        );
+    }
+
+    #[test]
+    fn regression_1() {
+        assert_eq!(
+            Solution::maximum_detonation(vec![vec![1, 1, 100000], vec![100000, 100000, 1]]),
+            1
+        );
+    }
+}