20250329 finished.

src/problem/mod.rs

@@ -566,3 +566,5 @@ mod p2829_determine_the_minimum_sum_of_a_k_avoiding_array;
 mod p2712_minimum_cost_to_make_all_characters_equal;
 
 mod p2716_minimize_string_length;
+
+mod p2360_longest_cycle_in_a_graph;

src/problem/p2360_longest_cycle_in_a_graph.rs

@@ -0,0 +1,55 @@
+/**
+ * [2360] Longest Cycle in a Graph
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn longest_cycle(edges: Vec<i32>) -> i32 {
+        let n = edges.len();
+        let mut labels = vec![0; n];
+
+        let mut current_label = 0;
+        let mut result = -1;
+
+        for i in 0..n {
+            if labels[i] != 0 {
+                continue;
+            }
+
+            let mut pos = i as i32;
+            let start_label = current_label;
+
+            while pos != -1 {
+                current_label += 1;
+                // 遇到已经遍历过的节点
+                let real_pos = pos as usize;
+                if labels[real_pos] != 0 {
+                    if labels[real_pos] > start_label {
+                        result = result.max(current_label - labels[real_pos]);
+                    }
+                    break;
+                }
+
+                labels[real_pos] = current_label;
+                pos = edges[real_pos];
+            }
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_2360() {
+        assert_eq!(3, Solution::longest_cycle(vec![3, 3, 4, 2, 3]));
+        assert_eq!(-1, Solution::longest_cycle(vec![2, -1, 3, 1]));
+    }
+}