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- Leetcode 3552. Grid Teleportation Traversal
- 1. 解题思路
- 2. 代码实现
- 题目链接：3552. Grid Teleportation Traversal
1. 解题思路
这一题的话核心就是一个广度优先遍历，我们只需要从原点开始，一点点考察其所能到达的位置，直至其最终到达终点即可。
唯一特殊的是，考虑到传送的存在，这里会有些特殊操作，不难发现，一个端口至多发生一次传送，否则必然可以优化路线，因此我们只需要考察每一个端口值上是否有过传送即可。
2. 代码实现
给出python代码实现如下：
class Solution:def minMoves(self, matrix: List[str]) -> int:n, m = len(matrix), len(matrix[0])teleportation = defaultdict(list)for i in range(n):for j in range(m):if matrix[i][j] in "#.":continueteleportation[matrix[i][j]].append((i, j))seen = {(0, 0)}q = [(0, 0, 0, 0)]def add_teleportation(step, i, j, status):nonlocal seen, qif matrix[i][j] not in "#." and (status & (1 << (ord(matrix[i][j]) - ord('A'))) == 0):for ti, tj in teleportation[matrix[i][j]]:if (ti, tj) not in seen:heapq.heappush(q, (step, ti, tj, status | (1 << (ord(matrix[i][j]) - ord('A')))))seen.add((ti, tj))returnadd_teleportation(0, 0, 0, 0)while q != []:step, i, j, status = heapq.heappop(q)if (i, j) == (n-1, m-1):return stepif i+1 < n and (i+1, j) not in seen and matrix[i+1][j] != "#":heapq.heappush(q, (step+1, i+1, j, status))seen.add((i+1, j))add_teleportation(step+1, i+1, j, status)if j+1 < m and (i, j+1 ) not in seen and matrix[i][j+1] != "#":heapq.heappush(q, (step+1, i, j+1, status))seen.add((i, j+1))add_teleportation(step+1, i, j+1, status)if i-1 >= 0 and (i-1, j) not in seen and matrix[i-1][j] != "#":heapq.heappush(q, (step+1, i-1, j, status))seen.add((i-1, j))add_teleportation(step+1, i-1, j, status)if j-1 >= 0 and (i, j-1 ) not in seen and matrix[i][j-1] != "#":heapq.heappush(q, (step+1, i, j-1, status))seen.add((i, j-1))add_teleportation(step+1, i, j-1, status)return -1
提交代码评测得到：耗时6943ms，占用内存147.7MB。