mergesort cluster

mergesort.c

 #include <stdlib.h>
+#include <mpi.h>
+#include <stdio.h>
 
 void merge(int* arr, int l, int m, int r, int* tmp) 
 {
@@ -34,15 +36,59 @@ void mergesort(int* arr, int l, int r, int* tmp)
   merge(arr, l, m, r, tmp);
 }
 
-int main(int argc, char const *argv[])
+int main(int argc, char *argv[])
 {
-  int x[] = {3, 5, 2, 6,8, 9, 1,0};
-  int* tmp = (int*) malloc(sizeof(int) * 8);
-  mergesort(x, 0, 8, tmp);
-  for (int i = 0; i < 8; ++i)
+  int n, i;
+  scanf("%d", &n);
+
+  int *arr = (int*) malloc(sizeof(int) * (n + 1));
+  for (i = 0; i < 8; ++i)
   {
-    printf("%d ", x[i]);
+    scanf("%d", &arr[i]);
   }
-  if (tmp != NULL) free(tmp);
+
+  int world_rank;
+  int world_size;
+  
+  MPI_Init(&argc, &argv);
+  MPI_Comm_rank(MPI_COMM_WORLD, &world_rank);
+  MPI_Comm_size(MPI_COMM_WORLD, &world_size);
+
+  int size = n / world_size;          // equally distributed
+  
+  int *arr_part = (int*) malloc(sizeof(int) * size);
+  MPI_Scatter(arr, size, MPI_INT, arr_part, size, MPI_INT, 0, MPI_COMM_WORLD);    // scatter to buckets
+  
+  int *tmp = (int*) malloc(sizeof(int) * size);
+  mergesort(arr_part, 0, size, tmp);
+  
+  int *sorted = NULL;
+  if(world_rank == 0) {
+    sorted = malloc(n * sizeof(int));
+  }
+  
+  MPI_Gather(arr_part, size, MPI_INT, sorted, size, MPI_INT, 0, MPI_COMM_WORLD);    // gather result
+  
+  if(world_rank == 0) 
+  {    
+    int *tmp2 = (int*) malloc(sizeof(int) * n);
+    mergesort(sorted, 0, n, tmp2);
+
+    for(i = 0; i < n; i++) 
+    {      
+      printf("%d ", sorted[i]);
+    }
+      
+    free(sorted);
+    free(tmp2);
+  }
+
+  free(arr);
+  free(arr_part);
+  free(tmp);
+
+  MPI_Barrier(MPI_COMM_WORLD);
+  MPI_Finalize();
+
   return 0;
 }
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