Sift Up a heap - C File

C examples for File:File Operation

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Description

Sift Up a heap

Demo Code

#include <stdio.h>
#include <stdlib.h>

#define MaxHeapSize 100//from   w ww.  j av a  2 s .  c o m

void siftUp(int[], int);
int num[MaxHeapSize + 1];

int main() {

   int n = 0, number;
   FILE * in = fopen("heap.in", "r");

   while (fscanf(in, "%d", &number) == 1) {
      if (n < MaxHeapSize) { //check if array has room
         num[++n] = number;
         siftUp(num, n);
      }
      else {
         printf("\nArray too small\n");
         exit(1);
      }
   }
   for (int h = 1; h <= n; h++) printf("%d ", num[h]);
   printf("\n");
   fclose(in);
}

void siftUp(int heap[], int n) {
 
   int siftItem = heap[n];
 
   int child = n;
 
   int parent = child / 2;
 
   while (parent > 0) {
      if (siftItem <= heap[parent]) 
         break;
      heap[child] = heap[parent]; //move down parent
      child = parent;
      parent = child / 2;
   }
   heap[child] = siftItem;
}

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