From dc614a018d58a641f36d2cdee48b766c1b37eaf6 Mon Sep 17 00:00:00 2001
From: kkunkka <kkunkka@zohomail.com>
Date: Sat, 26 Jul 2025 14:01:50 +0800
Subject: [PATCH] kk

---
 .../com/dota/gridGraph/_909/Solution.java     | 51 +++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 src/main/java/com/dota/gridGraph/_909/Solution.java

diff --git a/src/main/java/com/dota/gridGraph/_909/Solution.java b/src/main/java/com/dota/gridGraph/_909/Solution.java
new file mode 100644
index 0000000..9742337
--- /dev/null
+++ b/src/main/java/com/dota/gridGraph/_909/Solution.java
@@ -0,0 +1,51 @@
+package com.dota.gridGraph._909;
+
+import java.util.ArrayDeque;
+
+class Solution {
+	public int snakesAndLadders(int[][] board) {
+		var cnt = -1;
+		int n = board.length;
+		var book = new boolean[n * n + 1];
+		var queue = new ArrayDeque<Integer>();
+		queue.add(1);
+		while (!queue.isEmpty()) {
+			cnt++;
+			int size = queue.size();
+			for (int s = 0; s < size; s++) {
+				int p = queue.poll();
+				if (p == n * n) {
+					return cnt;
+				}
+				for (int i = 1; i <= 6 && p + i <= n * n; i++) {
+					var next = p + i;
+					if (book[next]) continue;
+					var xy = getXy(next, n);
+					var x = xy[0];
+					var y = xy[1];
+
+					book[next] = true;
+					if (board[x][y] == -1) {
+						queue.offer(next);
+						continue;
+					}
+
+					//跳到下一步
+					queue.offer(board[x][y]);
+				}
+			}
+		}
+		return -1;
+	}
+
+	// k是编号
+	// 从编号获取坐标
+	int[] getXy(int no, int n) {
+		var m = (no - 1) / n;
+		var l = (no - 1) % n;
+		if (m % 2 == 1) {
+			return new int[]{n - 1 - m, n - l - 1};
+		}
+		return new int[]{n - 1 - m, l};
+	}
+}
\ No newline at end of file