Leetcode 778. Swim in Rising Water

Find the minimum time t such that there is a 4-directional path from the top-left to bottom-right of an n×n grid using only cells with elevation ≤ t (water rises to level t). This is a minimax path problem — solvable by binary search with BFS/DFS or by Dijkstra/priority-queue that minimizes the maximum elevation along the path.