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fix: Handled empty graph, invalid input and added test cases for the same

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This commit is contained in:
Aditya Borate
2024-10-21 22:28:24 +05:30
parent 4f981e8c36
commit 12c94c126f
1 changed files with 35 additions and 15 deletions
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50
graph/number_of_paths.cpp
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@@ -32,27 +32,28 @@ namespace graph {
* @returns the number of paths from node `u` to node `v`
*/
std::uint32_t count_paths_dfs(const std::vector<std::vector<std::uint32_t>>& A,
std::uint32_t u,
std::uint32_t v,
std::uint32_t n,
std::vector<bool>& visited) {
std::uint32_t u,
std::uint32_t v,
std::uint32_t n,
std::vector<bool>& visited) {
if (u == v) {
return 1; // Base case: Reached the destination node
return 1; // Base case: Reached the destination node
}
visited[u] = true; // Mark the current node as visited
std::uint32_t path_count = 0; // Count of all paths from `u` to `v`
visited[u] = true; // Mark the current node as visited
std::uint32_t path_count = 0; // Count of all paths from `u` to `v`
for (std::uint32_t i = 0; i < n; i++) {
if (A[u][i] == 1 && !visited[i]) { // Check if there is an edge and the node is not visited
path_count += count_paths_dfs(A, i, v, n, visited); // Recursively explore paths from `i` to `v`
if (A[u][i] == 1 && !visited[i]) { // Check if there is an edge and the node is not visited
path_count += count_paths_dfs(A, i, v, n, visited); // Recursively explore paths from `i` to `v`
}
}
visited[u] = false; // Unmark the current node as visited (backtracking)
visited[u] = false; // Unmark the current node as visited (backtracking)
return path_count;
}
/**
* @brief Counts the number of paths from node `u` to node `v` in a directed graph
* using Depth First Search (DFS)
@@ -64,11 +65,16 @@ namespace graph {
* @returns the number of paths from node `u` to node `v`
*/
std::uint32_t count_paths(const std::vector<std::vector<std::uint32_t>>& A,
std::uint32_t u,
std::uint32_t v,
std::uint32_t n) {
std::vector<bool> visited(n, false); // Initialize a visited vector for tracking nodes
return count_paths_dfs(A, u, v, n, visited);
std::uint32_t u,
std::uint32_t v,
std::uint32_t n) {
// Check for invalid nodes or empty graph
if (u >= n || v >= n || A.empty() || A[0].empty()) {
return 0; // No valid paths if graph is empty or nodes are out of bounds
}
std::vector<bool> visited(n, false); // Initialize a visited vector for tracking nodes
return count_paths_dfs(A, u, v, n, visited); // Start DFS
}
} // namespace graph
@@ -118,6 +124,20 @@ static void test() {
std::uint32_t n4 = 1, u4 = 0, v4 = 0;
assert(graph::count_paths(graph4, u4, v4, n4) == 1); // There is self-loop, so 1 path from node 0 to 0
// Test case 5: Empty graph (no nodes, no paths)
std::vector<std::vector<std::uint32_t>> graph5 = {{}};
int n5 = 0, u5 = 0, v5 = 0;
assert(graph::count_paths(graph5, u5, v5, n5) == 0); // There are no paths in an empty graph
// Test case 6: Invalid nodes (out of bounds)
std::vector<std::vector<std::uint32_t>> graph6 = {
{0, 1, 0},
{0, 0, 1},
{0, 0, 0}
};
int n6 = 3, u6 = 0, v6 = 5; // Node `v` is out of bounds (n = 3, so valid indices are 0, 1, 2)
assert(graph::count_paths(graph6, u6, v6, n6) == 0); // Should return 0 because `v = 5` is invalid
std::cout << "All tests have successfully passed!\n";
}