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  1. #include<stdio.h>
  2. #include<stdlib.h>
  3. struct tree
  4. {
  5.     struct tree* left;
  6.     struct tree* right;
  7.     int x;
  8. };
  9. struct tree* makenode(int x) 
  10. {
  11.     struct tree * root =  malloc(sizeof(struct tree));
  12.     root -> x = x;
  13.     root -> left = root -> right = NULL;
  14.     return root;
  15. }
  16.  
  17. struct tree* makeBST(int *post, int start, int n, int inorder){
  18.     if(n <= 0)
  19.             return NULL;
  20.     int pivot = post[start + n -1];
  21.     struct tree * root = makenode(pivot);
  22.     root -> left = makeBST(post, start, pivot-1 - inorder, inorder );
  23.     root -> right = makeBST(post, pivot - inorder - 1, n - (pivot - inorder), pivot);
  24.     return root;
  25. }
  26. void preorder(struct tree* node)
  27. {
  28.     if(node == NULL)
  29.         return;
  30.     printf("%d ", node->x);
  31.     preorder(node->left);
  32.     preorder(node->right);
  33. }
  34. void printdot(struct tree* node, FILE * f)
  35. {
  36.     if(node == NULL)
  37.         return;
  38.     if(node-> left != NULL)
  39.     {
  40.         fprintf(f, "%d -- %d;\n", node->x, node->left->x);
  41.     }
  42.     if(node-> right != NULL)
  43.     {
  44.         fprintf(f, "%d -- %d;\n", node->x, node->right->x);
  45.     }
  46.     printdot(node->left, f);
  47.     printdot(node->right, f);
  48. }
  49.  
  50. int main(){
  51.     int i, n, *a;
  52.     printf("Enter n: ");
  53.     scanf("%d", &n);
  54.     a = malloc(n * sizeof(int));
  55.     printf ("Enter post order traversal: ");
  56.     for(i = 0; i < n; i++)
  57.     {
  58.         scanf("%d", &a[i]);
  59.     }
  60.     struct tree * tree = makeBST(a, 0, n, 0);
  61.     printf("Pre order traversal is : ");
  62.     preorder(tree);
  63.     printf("\n");
  64.     FILE * f = fopen("tree.dot", "w");
  65.     fprintf(f, "graph tree { \n");
  66.     printdot(tree, f);
  67.     fprintf(f, "}\n");
  68.     fclose(f);
  69. 	return 0;
  70. }
  71.  
Internal error #stdin #stdout 0s 0KB
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stdout
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Standard output is empty
https://ideone.com/BBEIIJ
language:
C (gcc 8.3)
created:
4 years ago
visibility:
public

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