diff --git a/cpp/kruskal.cpp b/cpp/kruskal.cpp new file mode 100644 index 000000000..d7ea8a292 --- /dev/null +++ b/cpp/kruskal.cpp @@ -0,0 +1,133 @@ +#include +using namespace std; + +class Edge { +public: + int src, dest, weight; +}; + +class Graph { +public: + + int V, E; + Edge* edge; +}; + +Graph* createGraph(int V, int E) { + Graph* graph = new Graph; + graph->V = V; + graph->E = E; + + graph->edge = new Edge[E]; + + return graph; +} + +class subset { +public: + int parent; + int rank; +}; + +int find(subset subsets[], int i) { + if (subsets[i].parent != i) + subsets[i].parent + = find(subsets, subsets[i].parent); + + return subsets[i].parent; +} + +void Union(subset subsets[], int x, int y) { + int xroot = find(subsets, x); + int yroot = find(subsets, y); + + if (subsets[xroot].rank < subsets[yroot].rank) + subsets[xroot].parent = yroot; + else if (subsets[xroot].rank > subsets[yroot].rank) + subsets[yroot].parent = xroot; + + else { + subsets[yroot].parent = xroot; + subsets[xroot].rank++; + } +} + +int myComp(const void* a, const void* b) { + Edge* a1 = (Edge*)a; + Edge* b1 = (Edge*)b; + return a1->weight > b1->weight; +} + +void KruskalMST(Graph* graph) { + int V = graph->V; + Edge result[V]; // Tnis will store the resultant MST + int e = 0; // An index variable, used for result[] + int i = 0; // An index variable, used for sorted edges + + qsort(graph->edge, graph->E, sizeof(graph->edge[0]), myComp); + + subset* subsets = new subset[(V * sizeof(subset))]; + + for (int v = 0; v < V; ++v) { + subsets[v].parent = v; + subsets[v].rank = 0; + } + + while (e < V - 1 && i < graph->E) { + Edge next_edge = graph->edge[i++]; + + int x = find(subsets, next_edge.src); + int y = find(subsets, next_edge.dest); + if (x != y) { + result[e++] = next_edge; + Union(subsets, x, y); + } + } + + cout << "Following are the edges in the constructed MST\n"; + int minimumCost = 0; + for (i = 0; i < e; ++i) + { + cout << result[i].src << " -- " << result[i].dest + << " == " << result[i].weight << endl; + minimumCost = minimumCost + result[i].weight; + } + cout << "Minimum Cost Spanning Tree: " << minimumCost<< endl; +} + +// Driver code +int main() { + int V = 4; // Number of vertices in graph + int E = 5; // Number of edges in graph + Graph* graph = createGraph(V, E); + + // add edge 0-1 + graph->edge[0].src = 0; + graph->edge[0].dest = 1; + graph->edge[0].weight = 10; + + // add edge 0-2 + graph->edge[1].src = 0; + graph->edge[1].dest = 2; + graph->edge[1].weight = 6; + + // add edge 0-3 + graph->edge[2].src = 0; + graph->edge[2].dest = 3; + graph->edge[2].weight = 5; + + // add edge 1-3 + graph->edge[3].src = 1; + graph->edge[3].dest = 3; + graph->edge[3].weight = 15; + + // add edge 2-3 + graph->edge[4].src = 2; + graph->edge[4].dest = 3; + graph->edge[4].weight = 4; + + + KruskalMST(graph); + + return 0; +}