From 8b0571e20980e44485b44e5b280c724ee6e67147 Mon Sep 17 00:00:00 2001
From: jackfiled <xcrenchangjun@outlook.com>
Date: Wed, 26 Jun 2024 17:53:47 +0800
Subject: [PATCH] 20240626 Finished

---
 src/problem/mod.rs                     |   3 +-
 src/problem/p909_snakes_and_ladders.rs | 100 +++++++++++++++++++++++++
 2 files changed, 102 insertions(+), 1 deletion(-)
 create mode 100644 src/problem/p909_snakes_and_ladders.rs

diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index 3252df0..9e08d91 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -158,4 +158,5 @@ mod p200_number_of_islands;
 mod p130_surrounded_regions;
 mod p399_evaluate_division;
 mod p207_course_schedule;
-mod p210_course_schedule_ii;
\ No newline at end of file
+mod p210_course_schedule_ii;
+mod p909_snakes_and_ladders;
\ No newline at end of file
diff --git a/src/problem/p909_snakes_and_ladders.rs b/src/problem/p909_snakes_and_ladders.rs
new file mode 100644
index 0000000..68b49d2
--- /dev/null
+++ b/src/problem/p909_snakes_and_ladders.rs
@@ -0,0 +1,100 @@
+/**
+ * [909] Snakes and Ladders
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::VecDeque;
+
+impl Solution {
+    pub fn snakes_and_ladders(board: Vec<Vec<i32>>) -> i32 {
+        let n = board.len() * board.len();
+        let mut map = Vec::with_capacity(n);
+        map.push(0);
+
+        let mut reverse = false;
+        let mut index = 1;
+
+        for array in board.iter().rev() {
+            let array: Box<dyn Iterator<Item = &i32>> = if reverse {
+                Box::new(array.iter().rev())
+            } else {
+                Box::new(array.iter())
+            };
+
+            for &i in array {
+                if i == -1 {
+                    map.push(index);
+                } else {
+                    map.push(i as usize);
+                }
+
+                index += 1;
+            }
+
+            reverse = !reverse;
+        }
+
+        let mut visited = vec![false; n + 1];
+        let mut queue = VecDeque::new();
+        queue.push_back(1);
+
+        let mut count = 0;
+        while !queue.is_empty() {
+            let length = queue.len();
+
+            for _ in 0..length {
+                let node = queue.pop_front().unwrap();
+
+                if node == n {
+                    return count;
+                }
+
+                for next in (node + 1)..=(node + 6) {
+                    if next > n {
+                        continue;
+                    }
+
+                    if !visited[next] {
+                        visited[next] = true;
+                        queue.push_back(map[next]);
+                    }
+                }
+            }
+
+            count += 1;
+        }
+
+        -1
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_909_1() {
+        assert_eq!(
+            Solution::snakes_and_ladders(vec![
+                vec![-1, -1, -1, -1, -1, -1],
+                vec![-1, -1, -1, -1, -1, -1],
+                vec![-1, -1, -1, -1, -1, -1],
+                vec![-1, 35, -1, -1, 13, -1],
+                vec![-1, -1, -1, -1, -1, -1],
+                vec![-1, 15, -1, -1, -1, -1]
+            ]),
+            4
+        );
+    }
+
+    #[test]
+    fn test_909_2() {
+        assert_eq!(
+            Solution::snakes_and_ladders(vec![vec![-1, -1, -1], vec![-1, 9, 8], vec![-1, 8, 9]]),
+            1
+        );
+    }
+}