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🔥Network Delay Time: Dijkstra Shortest Path DelayMedium
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MediumTrees & Graphs•Acceptance: 53.6%

Network Delay Time: Dijkstra Shortest Path Delay

Targeted in FAANG & Tech OA:UberGoogleAmazon
Real-World Engineering Context
Core to network packet routing (OSPF protocol), latency SLA analysis across AWS microservices, and Uber ETA calculation algorithms.
You are given a network of `n` nodes, labeled from `1` to `n`. You are also given `times`, a list of travel times as directed edges `times[i] = (ui, vi, wi)`, where `ui` is the source node, `vi` is the target node, and `wi` is the time it takes for a signal to travel from source to target. We will send a signal from a given node `k`. Return the **minimum time** it takes for all the `n` nodes to receive the signal. If it is impossible for all the `n` nodes to receive the signal, return `-1`.

Sample Test Cases

Input: [[[2,1,1],[2,3,1],[3,4,1]],4,2]
Expected: 2
Input: [[[1,2,1]],2,1]
Expected: 1
Input: [[[1,2,1]],2,2]
Expected: -1

Constraints

  • 1 <= k <= n <= 100
  • 1 <= times.length <= 6000
  • times[i].length == 3
  • 1 <= ui, vi <= n
  • ui != vi
  • 0 <= wi <= 100
  • All the pairs (ui, vi) are unique.
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