LeetCode 3898: Find the Degree of Each Vertex ·

Table of Contents

Meta Data
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Difficulty: easy First Attempt: 2026-04-12

Submissions: Accepted (first try)

Approach
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matrix[i][j] = 1 means an edge between i and j, so vertex i’s degree is the sum of row i. An undirected graph’s matrix is symmetric; I originally summed each column, which gives the same result.

My Solution
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class Solution:
    def findDegrees(self, matrix: List[List[int]]) -> List[int]:
        return [sum(row) for row in matrix]

Complexity
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Time O(n²), space O(n) for the output.

Mistakes to Avoid
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For a directed graph, row sums are outdegrees and column sums are indegrees; they cannot be swapped.

Interview Explanation
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Row i of the adjacency matrix records i’s neighbors, so each row’s sum is the degree. Time O(n²).

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Meta Data#

Approach#

My Solution#

Complexity#

Mistakes to Avoid#

Interview Explanation#

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