Count shortest distance in graph
Last updated: December 25, 2025
Quick Overview
Given a weighted, undirected graph represented as an adjacency list, write a function to calculate the shortest distance from a starting node to all other nodes in the graph using Dijkstra's algorithm. The function should return a dictionary where the keys are the node identifiers and the values are the shortest distances from the starting node. If a node is unreachable, its distance should be represented as infinity.
Zscaler
December 25, 2025376
11
2,645 solved
Given a weighted, undirected graph represented as an adjacency list, write a function to calculate the shortest distance from a starting node to all other nodes in the graph using Dijkstra's algorithm. The function should return a dictionary where the keys are the node identifiers and the values are the shortest distances from the starting node. If a node is unreachable, its distance should be represented as infinity.
This coding problem is frequently asked during Take-home Project at Zscaler. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Zscaler expects candidates to write production-quality code, not just solve the puzzle.
What the Interviewer Expects
- Identify the correct data structure and algorithm for the problem
- Write clean, bug-free code with proper variable naming
- Analyze time and space complexity correctly
- Handle basic edge cases (empty input, single element)
- Communicate your thought process while coding
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- How would you test this solution thoroughly?
- How would you modify your solution to handle streaming input?
- Can you optimize the space complexity of your solution?
- How would you parallelize this solution?
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Practice DSA ProblemsSample Answer
Problem Analysis
To solve the problem of finding the shortest distance from a starting node to all other nodes in a weighted, undirected graph, we will employ Dijkstra's algorithm. This algorithm is particularly s...
Approach
- Initialize Data Structures: We will create a distance dictionary to track the shortest distance from the starting node to each node, initializing all distances to infinity, except for the start...
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