Hi community, I've come across this problem: https://leetcode.com/problems/find-the-safest-path-in-a-grid/description/

Issue: I've come across a solution to this problem where we can apply modified Dijkstra's algo and also transition to 0-1 BFS method Solution link: https://leetcode.com/problems/find-the-safest-path-in-a-grid/solutions/5158996/c-rust-o-n-2-no-dijkstra-pure-bfs-explained-beats-97-44

But I'm unable to understand how is the Queue being Monotonic here in the solution provided in above link.