# Solution: Count the Number of Edges in an Undirected Graph

Let’s solve the Count the Number of Edges in an Undirected Graph problem.

## We'll cover the following

## Statement

Given an `n`

number of nodes in an undirected graph, compute the total number of bidirectional edges.

**Constraints:**

$0 \leq$ `n`

$\leq 10^2$ $0 \leq$ `edges.length`

$\leq n(n-1)/2$ `edges[i].length`

$== 2$ $1 \leq x,y \leq$ `n`

$x\neq y$ There are no multiple edges between any two vertices

There are no self-loops

## Solution

This approach iterates over each `vertex`

in the `graph`

and calculates the `sum`

of the lengths of `adjacency`

lists corresponding to each `vertex`

. The idea is to count the number of connections or edges in the `graph`

. Dividing the final `sum`

by `graph`

. This method effectively traverses the `adjacency`

list representation of the graph to determine the total number of edges.

Let’s look at the illustration below to better understand the solution:

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