# Sum of dependencies in a graph

Given a directed and connected graph with n nodes. If there is an edge from u to v then u depends on v. Our task was to find out the sum of dependencies for every node.

Example:

For the graph in diagram,

A depends on C and D i.e. 2

B depends on C i.e. 1

D depends on C i.e. 1

And C depends on none.

Hence answer -> 0 + 1 + 1 + 2 = 4

Asked in : Flipkart Interview

Idea is to check adjacency list and find how many edges are there from each vertex and return the total number of edges.

## C++

`// C++ program to find the sum of dependencies ` `#include <bits/stdc++.h> ` `using` `namespace` `std; ` ` ` `// To add an edge ` `void` `addEdge(vector <` `int` `> adj[], ` `int` `u,` `int` `v) ` `{ ` ` ` `adj[u].push_back(v); ` `} ` ` ` `// find the sum of all dependencies ` `int` `findSum(vector<` `int` `> adj[], ` `int` `V) ` `{ ` ` ` `int` `sum = 0; ` ` ` ` ` `// just find the size at each vector's index ` ` ` `for` `(` `int` `u = 0; u < V; u++) ` ` ` `sum += adj[u].size(); ` ` ` ` ` `return` `sum; ` `} ` ` ` `// Driver code ` `int` `main() ` `{ ` ` ` `int` `V = 4; ` ` ` `vector<` `int` `>adj[V]; ` ` ` `addEdge(adj, 0, 2); ` ` ` `addEdge(adj, 0, 3); ` ` ` `addEdge(adj, 1, 3); ` ` ` `addEdge(adj, 2, 3); ` ` ` ` ` `cout << ` `"Sum of dependencies is "` ` ` `<< findSum(adj, V); ` ` ` `return` `0; ` `} ` |

*chevron_right*

*filter_none*

## Java

`// Java program to find the sum of dependencies ` ` ` `import` `java.util.Vector; ` ` ` `class` `Test ` `{ ` ` ` `// To add an edge ` ` ` `static` `void` `addEdge(Vector <Integer> adj[], ` `int` `u,` `int` `v) ` ` ` `{ ` ` ` `adj[u].addElement((v)); ` ` ` `} ` ` ` ` ` `// find the sum of all dependencies ` ` ` `static` `int` `findSum(Vector<Integer> adj[], ` `int` `V) ` ` ` `{ ` ` ` `int` `sum = ` `0` `; ` ` ` ` ` `// just find the size at each vector's index ` ` ` `for` `(` `int` `u = ` `0` `; u < V; u++) ` ` ` `sum += adj[u].size(); ` ` ` ` ` `return` `sum; ` ` ` `} ` ` ` ` ` `// Driver method ` ` ` `public` `static` `void` `main(String[] args) ` ` ` `{ ` ` ` `int` `V = ` `4` `; ` ` ` `Vector<Integer> adj[] = ` `new` `Vector[V]; ` ` ` ` ` `for` `(` `int` `i = ` `0` `; i < adj.length; i++) { ` ` ` `adj[i] = ` `new` `Vector<>(); ` ` ` `} ` ` ` ` ` `addEdge(adj, ` `0` `, ` `2` `); ` ` ` `addEdge(adj, ` `0` `, ` `3` `); ` ` ` `addEdge(adj, ` `1` `, ` `3` `); ` ` ` `addEdge(adj, ` `2` `, ` `3` `); ` ` ` ` ` `System.out.println(` `"Sum of dependencies is "` `+ ` ` ` `findSum(adj, V)); ` ` ` `} ` `} ` `// This code is contributed by Gaurav Miglani ` |

*chevron_right*

*filter_none*

Output:

Sum of dependencies is 4

Time complexity : O(V) where V is number of vertices in graph.

This article is contributed by **Sahil Chhabra (akku)**. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

## Recommended Posts:

- Find the ordering of tasks from given dependencies
- Find whether it is possible to finish all tasks or not from given dependencies
- Convert the undirected graph into directed graph such that there is no path of length greater than 1
- Graph implementation using STL for competitive programming | Set 2 (Weighted graph)
- Detect cycle in the graph using degrees of nodes of graph
- Transpose graph
- Islands in a graph using BFS
- BFS for Disconnected Graph
- Hypercube Graph
- Bridges in a graph
- Biconnected graph
- Dominant Set of a Graph
- Graph and its representations
- A Peterson Graph Problem
- Coloring a Cycle Graph