Add plain old dijkstra implementation

dijkstra.c

+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <time.h>
+
+#define infinite 2147483646
+#define seed 13517119
+
+int **init_graph(int n){
+    int **matrix;
+    matrix = malloc(sizeof(int*) * n);
+    for(int i=0; i<n; i++){
+        matrix[i] = malloc(sizeof(int*) * n);
+    }
+
+    srand(seed);
+
+    for(int i=0; i<n; i++){
+        for(int j=0; j<n; j++){
+            if(i != j){
+                matrix[i][j] = rand() % 100;
+            }
+            else{
+                matrix[i][j] = 0;
+            }
+        }
+    }
+
+    return matrix;
+}
+
+void print_graph(int **matrix, int n, FILE *file){
+    for(int i=0; i<n; i++){
+        for(int j=0; j<n; j++){
+            fprintf(file, "%d ", matrix[i][j]);
+        }
+        fprintf(file, "\n");
+    }
+}
+
+void print_result(int *dist, int source, int n, FILE *file){
+    for(int i=0; i<n; i++){
+        fprintf(file, "Node %d to %d : %d \n", (source + 1), (i + 1), dist[i]);
+    }
+}
+
+int minDistance(int *dist, bool sptSet[], int n) 
+{ 
+    // Initialize min value 
+    int min = infinite, min_index; 
+
+    for (int v = 0; v < n; v++) 
+        if (sptSet[v] == false && dist[v] <= min) 
+            min = dist[v], min_index = v; 
+
+    return min_index; 
+} 
+
+int *dijkstra(int **graph, int src, int n) 
+{ 
+    int *dist; // The output array.  dist[i] will hold the shortest 
+    // distance from src to i
+
+    dist = malloc(sizeof(int) * n);
+
+    bool *sptSet; // sptSet[i] will be true if vertex i is included in shortest 
+    // path tree or shortest distance from src to i is finalized 
+    sptSet = malloc(sizeof(bool) * n);
+
+    // Initialize all distances as INFINITE and stpSet[] as false 
+    for (int i = 0; i < n; i++) 
+        dist[i] = infinite, sptSet[i] = false; 
+
+    // Distance of source vertex from itself is always 0 
+    dist[src] = 0; 
+
+    // Find shortest path for all vertices 
+    for (int count = 0; count < n - 1; count++) { 
+        // Pick the minimum distance vertex from the set of vertices not 
+        // yet processed. u is always equal to src in the first iteration. 
+        int u = minDistance(dist, sptSet, n); 
+
+        // Mark the picked vertex as processed 
+        sptSet[u] = true; 
+
+        // Update dist value of the adjacent vertices of the picked vertex. 
+        for (int v = 0; v < n; v++) 
+
+            // Update dist[v] only if is not in sptSet, there is an edge from 
+            // u to v, and total weight of path from src to  v through u is 
+            // smaller than current value of dist[v] 
+            if (!sptSet[v] && graph[u][v] && dist[u] != infinite 
+                && dist[u] + graph[u][v] < dist[v]) 
+                dist[v] = dist[u] + graph[u][v]; 
+    } 
+
+    return dist; 
+} 
+
+int main(int argc, char **argv){
+    int n;
+    int **matrix;
+    int *result;
+    FILE *fileopen;
+
+    fileopen = fopen("output.txt", "w");
+
+    clock_t start_t, end_t;
+    double diff_t;
+
+    n = atoi(argv[1]);
+
+    matrix = init_graph(n);
+    print_graph(matrix, n, fileopen);
+
+    start_t = clock();
+
+    for(int i=0; i<n; i++){
+        result = dijkstra(matrix, i, n);
+        print_result(result, i, n, fileopen);
+    }
+    
+    end_t = clock();
+    diff_t = (double)(end_t-start_t) / CLOCKS_PER_SEC * 1000000;
+
+    printf("Execution time : %f microseconds\n", diff_t);
+
+    free(result);
+    
+    for(int i=0; i<n; i++){
+        int* current = matrix[i];
+        free(current);
+    }
+
+    free(matrix);
+
+    fclose(fileopen);
+
+    return 0;
+}
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