月度归档： 2021 年 12 月

void sort(float arr[], unsigned int N)
  { // heapsort algorithm
      unsigned int n = N, i = n/2, parent, child;
      int t;

      for (;;) { /* Loops until arr is sorted */
          if (i > 0) { /* First stage - Sorting the heap */
              i--;           /* Save its index to i */
              t = arr[i];    /* Save parent value to t */
          } else {     /* Second stage - Extracting elements in-place */
              n--;           /* Make the new heap smaller */
              if (n == 0) return; /* When the heap is empty, we are done */
              t = arr[n];    /* Save last value (it will be overwritten) */
              arr[n] = arr[0]; /* Save largest value at the end of arr */
          }

          parent = i; /* We will start pushing down t from parent */
          child = i*2 + 1; /* parent's left child */

          /* Sift operation - pushing the value of t down the heap */
          while (child < n) {
              if (child + 1 < n  &&  arr[child + 1] > arr[child]) {
                  child++; /* Choose the largest child */
              }
              if (arr[child] > t) { /* If any child is bigger than the parent */
                  arr[parent] = arr[child]; /* Move the largest child up */
                  parent = child; /* Move parent pointer to this child */
                  //child = parent*2-1; /* Find the next child */
                  child = parent*2+1; /* the previous line is wrong*/
              } else {
                  break; /* t's place is found */
              }
          }
          arr[parent] = t; /* We save t in the heap */
      }
  }

#include <math.h>

int ifindi(int n,int arr[],int v)
{
    int i,begin=0,end=n-1,mid;

    if(v<arr[0] || v>arr[n-1])
        return -9;
    if(n<=0)
        return -9;

//    mid=rint((end-begin)/2);
    while(1)
    {
        if((end-begin)<=1){
            if(arr[begin]==v) return begin;
            if(arr[end]==v) return end;
        }
        mid=begin+rint((end-begin)/2);
//        printf("mid=%d\n",mid);
        if(v>=arr[begin] && v<arr[mid]) end=mid;
        if(v>=arr[mid] && v<=arr[end]) begin=mid;
//        printf("begin=%d, end=%d\n",begin,end);
    }
}