Counting the sum of every nodes’ neighbors’ degrees?

For each node u in an undirected graph, let twodegree[u] be the sum of the degrees of u’s neighbors. Show how to compute the entire array of twodegree[.] values in linear time, given a graph in adjacency list format.

This is the solution

for all u ∈  V :
  degree[u] = 0
  for all (u; w) ∈  E:
    degree[u] = degree[u] + 1
for all u ∈  V :
  twodegree[u] = 0
  for all (u; w) ∈  E:
    twodegree[u] = twodegree[u] + degree[w]

can someone explain what degree[u] does in this case and how twodegree[u] = twodegree[u] + degree[w] is supposed to be the sum of the degrees of u’s neighbors?

Related Posts:

  1. In a triangulated isometric grid, what triangle is a given point in?
  2. Breadth First Search time complexity analysis
  3. Difference and advantages between dijkstra & A star
  4. Is Dijkstra’s algorithm for directed or undirected graphs?
  5. What is a loop invariant?
  6. What is a loop invariant?
  7. What does O(log n) mean exactly?
  8. how to calculate binary search complexity
  9. When is it practical to use Depth-First Search (DFS) vs Breadth-First Search (BFS)? [closed]
  10. What does O(log n) mean exactly?
  11. What is Sliding Window Algorithm? Examples?
  12. Quicksort with Python
  13. What is the difference between tree depth and height?
  14. how to implement quick sort algorithm in C++
  15. Python: maximum recursion depth exceeded while calling a Python object
  16. Algorithms in O(n^2) vs O(n) [duplicate]
  17. Understanding Time complexity calculation for Dijkstra Algorithm
  18. Why is the time complexity of both DFS and BFS O( V + E )
  19. Time complexity of a Priority Queue in C++
  20. What is stability in sorting algorithms and why is it important?
  21. Time Complexity of the Kruskal Algorithm?
  22. Quick Sort Vs Merge Sort
  23. Polynomial time and exponential time
  24. Insertion Sort vs. Selection Sort
  25. Best Case for Bubble Sort
  26. How to find the kth smallest element in the union of two sorted arrays?
  27. Big O, how do you calculate/approximate it?
  28. Performing Breadth First Search recursively
  29. Is Quicksort in-place or not?
  30. longest increasing subsequence(O(nlogn))
  31. O(n log n) vs O(n) — practical differences in time complexity
  32. When should I use Kruskal as opposed to Prim (and vice versa)?
  33. Trying to understand max heapify
  34. Shortest possible depth of a leaf in decision tree (comparison sorting algorithm)
  35. Python Weighted Random [duplicate]
  36. What is the meaning of “exclusive” and “inclusive” when describing number ranges?
  37. What’s a good algorithm to generate a maze?
  38. Intuition for perceptron weight update rule
  39. Easy: Solve T(n)=T(n-1)+n by Iteration Method
  40. Good Java graph algorithm library?
  41. What is tail call optimization?
  42. PacMan: what kinds of heuristics are mainly used?
  43. Quicksort vs heapsort
  44. Big-oh vs big-theta
  45. Best case time complexity for selection sort
  46. Looking for algorithm finding euler path
  47. Trie complexity and searching
  48. What does this definition of contiguous subsequences mean?
  49. Is log(n!) = Θ(n·log(n))?
  50. Is complexity O(log(n)) equivalent to O(sqrt(n))?
  51. How to find maximum spanning tree?
  52. Exactly how many comparisons does merge sort make?
  53. Algorithm to return all combinations of k elements from n
  54. How to calculate big-theta
  55. What is the time complexity of while loops?
  56. Merge sort time and space complexity
  57. Intuitive explanation for why QuickSort is n log n?
  58. Calculate distance between two latitude-longitude points? (Haversine formula)
  59. Shuffle a deck of cards in Java
  60. How to calculate time complexity of backtracking algorithm?
  61. Median of Medians in Java
  62. What is a loop invariant?
  63. Hash table runtime complexity (insert, search and delete)
  64. Which is better: O(n log n) or O(n^2)
  65. What is O(log* N)?
  66. Quickselect time complexity explained
  67. What is the proper equivalent of “while(true)” in plain C?
  68. Bellman-Ford vs Dijkstra: Under what circumstances is Bellman-Ford better?
  69. Asymptotic Notation – does n (log n) (log n) simplify?
  70. Difference between Big-O and Little-O Notation
  71. What is the big-O of the function (log n)^k
  72. How to calculate an angle from three points?
  73. Why is O(n) better than O( nlog(n) )?
  74. How to solve: T(n) = T(n/2) + T(n/4) + T(n/8) + (n)
  75. Is there an O(n) integer sorting algorithm?
  76. An example of Best Case Scenario for Quick Sort (Need someone to check if my answer is correct)
  77. how to write a recurrence relation for a given piece of code
  78. Why is merge sort worst case run time O (n log n)?
  79. Why is merge sort worst case run time O (n log n)?
  80. What is the time and space complexity of a breadth first and depth first tree traversal?
  81. Create your own MD5 collisions
  82. Image Segmentation using Mean Shift explained
  83. Finding the median of an unsorted array
  84. Difference between Big-Theta and Big O notation in simple language
  85. What is the difference between bucket sort and radix sort?
  86. How are the following functions O(N^3)?
  87. Difference between O(n) and O(log(n)) – which is better and what exactly is O(log(n))?
  88. Finding all possible combinations of numbers to reach a given sum
  89. Are there any real O(n^n) algorithms?
  90. Sorting an array in C?
  91. How to determine if a point is in a 2D triangle?
  92. Modular multiplicative inverse function in Python
  93. Minesweeper solving algorithm
  94. About bubble sort vs merge sort
  95. Kadane’s algorithm explained
  96. Unfamiliar symbol in algorithm: what does ∀ mean? [closed]
  97. Dijkstra’s algorithm in python
  98. Is it more efficient to copy a vector by reserving and copying, or by creating and swapping? [duplicate]
  99. How to replace all occurrences of a character in string?
  100. Weighted random selection from array

Leave a Comment