fix: linter warnings for topological_sort. (#994)

Approving for now to enable a PR that adds graph folder to the CI build system.

graph/topological_sort.cpp

@@ -1,47 +1,48 @@
 #include <algorithm>
 #include <iostream>
 #include <vector>
-using namespace std;
 
-int n, m;  // For number of Vertices (V) and number of edges (E)
-vector<vector<int>> G;
-vector<bool> visited;
-vector<int> ans;
+int number_of_vertices, number_of_edges;  // For number of Vertices (V) and number of edges (E)
+std::vector<std::vector<int>> graph;
+std::vector<bool> visited;
+std::vector<int> topological_order;
 
 void dfs(int v) {
     visited[v] = true;
-    for (int u : G[v]) {
-        if (!visited[u])
+    for (int u : graph[v]) {
+        if (!visited[u]) {
             dfs(u);
         }
-    ans.push_back(v);
+    }
+    topological_order.push_back(v);
 }
 
 void topological_sort() {
-    visited.assign(n, false);
-    ans.clear();
-    for (int i = 0; i < n; ++i) {
-        if (!visited[i])
+    visited.assign(number_of_vertices, false);
+    topological_order.clear();
+    for (int i = 0; i < number_of_vertices; ++i) {
+        if (!visited[i]) {
             dfs(i);
         }
-    reverse(ans.begin(), ans.end());
+    }
+    reverse(topological_order.begin(), topological_order.end());
 }
 int main() {
-    cout << "Enter the number of vertices and the number of directed edges\n";
-    cin >> n >> m;
-    int x, y;
-    G.resize(n, vector<int>());
-    for (int i = 0; i < n; ++i) {
-        cin >> x >> y;
+    std::cout << "Enter the number of vertices and the number of directed edges\n";
+    std::cin >> number_of_vertices >> number_of_edges;
+    int x = 0, y = 0;
+    graph.resize(number_of_vertices, std::vector<int>());
+    for (int i = 0; i < number_of_edges; ++i) {
+        std::cin >> x >> y;
         x--, y--;  // to convert 1-indexed to 0-indexed
-        G[x].push_back(y);
+        graph[x].push_back(y);
     }
     topological_sort();
-    cout << "Topological Order : \n";
-    for (int v : ans) {
-        cout << v + 1
+    std::cout << "Topological Order : \n";
+    for (int v : topological_order) {
+        std::cout << v + 1
              << ' ';  // converting zero based indexing back to one based.
     }
-    cout << '\n';
+    std::cout << '\n';
     return 0;
 }