From a003b350006642c29b3d3acf5f875c8b457d722b Mon Sep 17 00:00:00 2001 From: Rimjhim Bhadani Date: Sat, 26 Oct 2019 01:49:53 +0530 Subject: [PATCH] Create Pims.java --- Graphs/Pims.java | 105 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 105 insertions(+) create mode 100644 Graphs/Pims.java diff --git a/Graphs/Pims.java b/Graphs/Pims.java new file mode 100644 index 0000000..829ed5c --- /dev/null +++ b/Graphs/Pims.java @@ -0,0 +1,105 @@ +import java.util.*; +import java.lang.*; +import java.io.*; + +class MST { + // Number of vertices in the graph + private static final int V = 5; + + // A utility function to find the vertex with minimum key + // value, from the set of vertices not yet included in MST + int minKey(int key[], Boolean mstSet[]) + { + // Initialize min value + int min = Integer.MAX_VALUE, min_index = -1; + + for (int v = 0; v < V; v++) + if (mstSet[v] == false && key[v] < min) { + min = key[v]; + min_index = v; + } + + return min_index; + } + + // A utility function to print the constructed MST stored in + // parent[] + void printMST(int parent[], int graph[][]) + { + System.out.println("Edge \tWeight"); + for (int i = 1; i < V; i++) + System.out.println(parent[i] + " - " + i + "\t" + graph[i][parent[i]]); + } + + // Function to construct and print MST for a graph represented + // using adjacency matrix representation + void primMST(int graph[][]) + { + // Array to store constructed MST + int parent[] = new int[V]; + + // Key values used to pick minimum weight edge in cut + int key[] = new int[V]; + + // To represent set of vertices not yet included in MST + Boolean mstSet[] = new Boolean[V]; + + // Initialize all keys as INFINITE + for (int i = 0; i < V; i++) { + key[i] = Integer.MAX_VALUE; + mstSet[i] = false; + } + + // Always include first 1st vertex in MST. + key[0] = 0; // Make key 0 so that this vertex is + // picked as first vertex + parent[0] = -1; // First node is always root of MST + + // The MST will have V vertices + for (int count = 0; count < V - 1; count++) { + // Pick thd minimum key vertex from the set of vertices + // not yet included in MST + int u = minKey(key, mstSet); + + // Add the picked vertex to the MST Set + mstSet[u] = true; + + // Update key value and parent index of the adjacent + // vertices of the picked vertex. Consider only those + // vertices which are not yet included in MST + for (int v = 0; v < V; v++) + + // graph[u][v] is non zero only for adjacent vertices of m + // mstSet[v] is false for vertices not yet included in MST + // Update the key only if graph[u][v] is smaller than key[v] + if (graph[u][v] != 0 && mstSet[v] == false && graph[u][v] < key[v]) { + parent[v] = u; + key[v] = graph[u][v]; + } + } + + // print the constructed MST + printMST(parent, graph); + } + + public static void main(String[] args) + { + /* Let us create the following graph + 2 3 + (0)--(1)--(2) + | / \ | + 6| 8/ \5 |7 + | / \ | + (3)-------(4) + 9 */ + MST t = new MST(); + int graph[][] = new int[][] { { 0, 2, 0, 6, 0 }, + { 2, 0, 3, 8, 5 }, + { 0, 3, 0, 0, 7 }, + { 6, 8, 0, 0, 9 }, + { 0, 5, 7, 9, 0 } }; + + // Print the solution + t.primMST(graph); + } +}