Add Floyd Warshall algorithm in C++

Author: Hardvan

README.md

@@ -130,8 +130,8 @@ In order to achieve greater coverage and encourage more people to contribute to
                 </a>
             </td>
             <td> <!-- C++ -->
-                <a href="./CONTRIBUTING.md">
-                    <img align="center" height="25" src="./logos/github.svg" />
+                <a href="./src/cpp/FloydWarshall.cpp">
+                    <img align="center" height="25" src="./logos/cplusplus.svg" />
                 </a>
             </td>
             <td> <!-- Java -->

src/cpp/FloydWarshall.cpp

@@ -0,0 +1,71 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+// Function to display the matrix
+void showMatrix(const vector<vector<long>> &matrix, int numVertices)
+{
+    for (int i = 0; i < numVertices; i++)
+    {
+        for (int j = 0; j < numVertices; j++)
+        {
+            if (matrix[i][j] < 10) // For better alignment
+                cout << " ";
+            cout << matrix[i][j] << " ";
+        }
+        cout << endl;
+    }
+    cout << endl;
+}
+
+// Floyd-Warshall algorithm
+void floydWarshall(vector<vector<long>> &matrix, int n)
+{
+    for (int k = 0; k < n; k++) // Intermediary vertex
+    {
+        for (int i = 0; i < n; i++) // Origin vertex
+        {
+            for (int j = 0; j < n; j++) // Destination vertex
+            {
+                if (matrix[i][k] != LONG_MAX &&                 // i -> k exists
+                    matrix[k][j] != LONG_MAX &&                 // k -> j exists
+                    matrix[i][j] > matrix[i][k] + matrix[k][j]) // i -> j is shorter via k
+                {
+                    matrix[i][j] = matrix[i][k] + matrix[k][j]; // Update i -> j
+                }
+            }
+        }
+    }
+}
+
+int main()
+{
+    int numVertices = 5;
+
+    // Initialize matrix with given values
+    vector<vector<long>> matrix = {
+        {0, 2, 10, 5, 7},
+        {2, 0, 3, 3, 1},
+        {10, 3, 0, 1, 2},
+        {5, 3, 1, 0, LONG_MAX},
+        {7, 1, 2, 2, 0}};
+
+    // Display the original matrix
+    cout << "Original matrix:" << endl;
+    showMatrix(matrix, numVertices);
+
+    // Apply Floyd-Warshall algorithm
+    floydWarshall(matrix, numVertices);
+
+    // Display the updated matrix
+    cout << "Updated matrix:" << endl;
+    showMatrix(matrix, numVertices);
+
+    // Show all shortest paths in 3 columns: source, destination, shortest distance
+    cout << "Source\tDestination\tShortest Distance" << endl;
+    for (int i = 0; i < numVertices; i++)
+        for (int j = 0; j < numVertices; j++)
+            cout << i << "\t" << j << "\t\t" << matrix[i][j] << endl;
+
+    return 0;
+}