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Print all paths from a given source to a destination using BFS
• Difficulty Level : Medium
• Last Updated : 24 Dec, 2020

Given a directed graph, a source vertex ‘src’ and a destination vertex ‘dst’, print all paths from given ‘src’ to ‘dst’.

Consider the following directed graph. Let the src be 2 and dst be 3. There are 3 different paths from 2 to 3. We have already discussed Print all paths from a given source to a destination using DFS.
Below is BFS based solution.

Algorithm :

```create a queue which will store path(s) of type vector
initialise the queue with first path starting from src

Now run a loop till queue is not empty
get the frontmost path from queue
check if the lastnode of this path is destination
if true then print the path
run a loop for all the vertices connected to the
current vertex i.e. lastnode extracted from path
if the vertex is not visited in current path
a) create a new path from earlier path and
append this vertex
b) insert this new path to queue```

## C++

 `// C++ program to print all paths of source to``// destination in given graph``#include ``using` `namespace` `std;` `// utility function for printing``// the found path in graph``void` `printpath(vector<``int``>& path)``{``    ``int` `size = path.size();``    ``for` `(``int` `i = 0; i < size; i++)``        ``cout << path[i] << ``" "``;   ``    ``cout << endl;``}` `// utility function to check if current``// vertex is already present in path``int` `isNotVisited(``int` `x, vector<``int``>& path)``{``    ``int` `size = path.size();``    ``for` `(``int` `i = 0; i < size; i++)``        ``if` `(path[i] == x)``            ``return` `0;``    ``return` `1;``}` `// utility function for finding paths in graph``// from source to destination``void` `findpaths(vector >&g, ``int` `src,``                                 ``int` `dst, ``int` `v)``{``    ``// create a queue which stores``    ``// the paths``    ``queue > q;` `    ``// path vector to store the current path``    ``vector<``int``> path;``    ``path.push_back(src);``    ``q.push(path);``    ``while` `(!q.empty()) {``        ``path = q.front();``        ``q.pop();``        ``int` `last = path[path.size() - 1];` `        ``// if last vertex is the desired destination``        ``// then print the path``        ``if` `(last == dst)``            ``printpath(path);       ` `        ``// traverse to all the nodes connected to``        ``// current vertex and push new path to queue``        ``for` `(``int` `i = 0; i < g[last].size(); i++) {``            ``if` `(isNotVisited(g[last][i], path)) {``                ``vector<``int``> newpath(path);``                ``newpath.push_back(g[last][i]);``                ``q.push(newpath);``            ``}``        ``}``    ``}``}` `// driver program``int` `main()``{``    ``vector > g;``    ``// number of vertices``    ``int` `v = 4;``    ``g.resize(4);` `    ``// construct a graph``    ``g.push_back(3);``    ``g.push_back(1);``    ``g.push_back(2);``    ``g.push_back(3);``    ``g.push_back(0);``    ``g.push_back(1);` `    ``int` `src = 2, dst = 3;``    ``cout << ``"path from src "` `<< src``         ``<< ``" to dst "` `<< dst << ``" are \n"``;` `    ``// function for finding the paths``    ``findpaths(g, src, dst, v);` `    ``return` `0;``}`

## Python3

 `# Python3 program to print all paths of``# source to destination in given graph``from` `typing ``import` `List``from` `collections ``import` `deque` `# Utility function for printing``# the found path in graph``def` `printpath(path: ``List``[``int``]) ``-``> ``None``:``    ` `    ``size ``=` `len``(path)``    ``for` `i ``in` `range``(size):``        ``print``(path[i], end ``=` `" "``)``        ` `    ``print``()` `# Utility function to check if current``# vertex is already present in path``def` `isNotVisited(x: ``int``, path: ``List``[``int``]) ``-``> ``int``:` `    ``size ``=` `len``(path)``    ``for` `i ``in` `range``(size):``        ``if` `(path[i] ``=``=` `x):``            ``return` `0``            ` `    ``return` `1` `# Utility function for finding paths in graph``# from source to destination``def` `findpaths(g: ``List``[``List``[``int``]], src: ``int``,``              ``dst: ``int``, v: ``int``) ``-``> ``None``:``                  ` `    ``# Create a queue which stores``    ``# the paths``    ``q ``=` `deque()` `    ``# Path vector to store the current path``    ``path ``=` `[]``    ``path.append(src)``    ``q.append(path.copy())``    ` `    ``while` `q:``        ``path ``=` `q.popleft()``        ``last ``=` `path[``len``(path) ``-` `1``]` `        ``# If last vertex is the desired destination``        ``# then print the path``        ``if` `(last ``=``=` `dst):``            ``printpath(path)` `        ``# Traverse to all the nodes connected to``        ``# current vertex and push new path to queue``        ``for` `i ``in` `range``(``len``(g[last])):``            ``if` `(isNotVisited(g[last][i], path)):``                ``newpath ``=` `path.copy()``                ``newpath.append(g[last][i])``                ``q.append(newpath)` `# Driver code``if` `__name__ ``=``=` `"__main__"``:``    ` `    ``# Number of vertices``    ``v ``=` `4``    ``g ``=` `[[] ``for` `_ ``in` `range``(``4``)]` `    ``# Construct a graph``    ``g[``0``].append(``3``)``    ``g[``0``].append(``1``)``    ``g[``0``].append(``2``)``    ``g[``1``].append(``3``)``    ``g[``2``].append(``0``)``    ``g[``2``].append(``1``)` `    ``src ``=` `2``    ``dst ``=` `3``    ``print``(``"path from src {} to dst {} are"``.``format``(``        ``src, dst))` `    ``# Function for finding the paths``    ``findpaths(g, src, dst, v)` `# This code is contributed by sanjeev2552`

Output:

```path from src 2 to dst 3 are
2 0 3
2 1 3
2 0 1 3```

This article is contributed by Mandeep Singh. 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.
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