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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3.  
  4. int binary_search(int a[], int n, int x){
  5.  
  6.     int lef = 0;
  7.     int rig = n - 1;
  8.     int mid;
  9.  
  10.     while(lef <= rig){
  11.  
  12.         mid = (lef + rig) / 2;
  13.  
  14.         if(a[mid] == x){
  15.             return mid;
  16.         }
  17.         else if(x < a[mid]){
  18.             rig = mid - 1;
  19.         }
  20.         else{
  21.             lef = mid + 1;
  22.         }
  23.     }
  24.  
  25.     return -1;
  26. }
  27.  
  28. int main(void){
  29.     int n,x,i;
  30.     int *a;
  31.     int ans=-1;
  32.  
  33.     scanf("%d %d",&n,&x);
  34.  
  35.     a=(int*)malloc(sizeof(int)*n);
  36.  
  37.     for(i=0;i<n;i++){
  38.         scanf("%d",&a[i]);
  39.     }
  40.  
  41.     ans=binary_search(a,n,x);
  42.  
  43.     if(ans!=-1)
  44.         printf("a[%d] = %d\n",ans,a[ans]);
  45.     else
  46.         printf("not found\n");
  47.  
  48.     free(a);
  49.     return 0;
  50. }
Success #stdin #stdout 0s 5324KB
comments (?)
stdin
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12 5
1 2 3 4 5 8 9 13 16 21 25 27
stdout
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a[4] = 5
https://ideone.com/gNYh3J
language:
C (gcc 8.3)
created:
3 hours ago
visibility:
public

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