A small office network has n switches labelled 0 .. n-1. Links are directed: links[i] = [u, v, ms]
means packets can travel from u to v with a latency of ms milliseconds (ms >= 0). Parallel links
are possible.
Return an n x n table t where t[u][v] is the smallest total latency from u to v,
t[u][u] = 0, and -1 marks pairs with no route.
Examples
Input: n = 3, links = [[0,1,5],[1,2,2],[0,2,9]]
Output: [[0, 5, 7], [-1, 0, 2], [-1, -1, 0]]
Explanation: 0 -> 1 -> 2 costs 7, cheaper than the direct link (9). Nothing leads back to 0.
Input: n = 2, links = [[0,1,3],[0,1,1],[1,0,4]]
Output: [[0, 1], [4, 0]]
Constraints
1 <= n <= 60,0 <= len(links) <= 2000,0 <= ms <= 10**6- Target
O(n**3)time.
Goals
- Initialise a distance matrix from a directed edge list
- Apply the Floyd-Warshall triple loop in the correct order
- Translate infinity back into a sentinel