mirror of
https://github.com/TheAlgorithms/C
synced 2024-11-22 13:31:21 +03:00
105 lines
2.3 KiB
C
105 lines
2.3 KiB
C
#include<stdio.h>
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#include<stdlib.h>
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#include<limits.h>
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#include<string.h>
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//Structure for storing a graph
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struct Graph{
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int vertexNum;
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int** edges;
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};
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//Constructs a graph with V vertices and E edges
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void createGraph(struct Graph* G,int V){
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G->vertexNum = V;
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G->edges =(int**) malloc(V * sizeof(int*));
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for(int i=0; i<V; i++){
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G->edges[i] = (int*) malloc(V * sizeof(int));
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for(int j=0; j<V; j++)
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G->edges[i][j] = INT_MAX;
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G->edges[i][i] = 0;
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}
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}
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//Adds the given edge to the graph
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void addEdge(struct Graph* G, int src, int dst, int weight){
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G->edges[src][dst] = weight;
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}
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//Utility function to print distances
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void print(int dist[], int V){
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printf("\nThe Distance matrix for Floyd - Warshall\n");
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for(int i = 0; i < V; i++){
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for(int j=0; j<V; j++){
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if(dist[i*V+j] != INT_MAX)
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printf("%d\t",dist[i*V+j]);
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else
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printf("INF\t");
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}
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printf("\n");
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}
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}
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//The main function that finds the shortest path from a vertex
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//to all other vertices using Floyd-Warshall Algorithm.
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void FloydWarshall(struct Graph* graph){
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int V = graph->vertexNum;
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int dist[V][V];
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//Initialise distance array
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for(int i=0; i<V; i++)
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for(int j=0; j<V; j++)
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dist[i][j] = graph->edges[i][j];
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//Calculate distances
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for(int k=0; k<V; k++)
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//Choose an intermediate vertex
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for(int i=0; i<V; i++)
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//Choose a source vertex for given intermediate
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for(int j=0; j<V; j++)
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//Choose a destination vertex for above source vertex
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if(dist[i][k] != INT_MAX && dist[k][j] != INT_MAX && dist[i][k] + dist[k][j] < dist[i][j])
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//If the distance through intermediate vertex is less than direct edge then update value in distance array
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dist[i][j] = dist[i][k] + dist[k][j];
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//Convert 2d array to 1d array for print
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int dist1d[V*V];
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for(int i=0; i<V; i++)
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for(int j=0; j<V; j++)
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dist1d[i*V+j] = dist[i][j];
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print(dist1d,V);
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}
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//Driver Function
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int main(){
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int V,E;
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int src,dst,weight;
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struct Graph G;
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printf("Enter number of vertices: ");
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scanf("%d",&V);
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printf("Enter number of edges: ");
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scanf("%d",&E);
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createGraph(&G,V);
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for(int i=0; i<E; i++){
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printf("\nEdge %d \nEnter source: ",i+1);
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scanf("%d",&src);
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printf("Enter destination: ");
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scanf("%d",&dst);
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printf("Enter weight: ");
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scanf("%d",&weight);
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addEdge(&G, src, dst, weight);
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}
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FloydWarshall(&G);
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return 0;
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}
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