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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3.  
  4. //この関数を実装する
  5. int binary_search(int a[],int n,int x){
  6.  
  7. int lef, rig, mid;
  8. lef=0;
  9. rig=n-1;
  10. int ret=-1;
  11.  
  12. while(lef<=rig){
  13. mid=(lef+rig)/2;
  14. if(a[mid]==x){
  15. ret=mid;
  16.  break;
  17. }
  18. if(x<a[mid])
  19. rig = mid-1;
  20. else lef = mid+1;
  21. }
  22.  return ret;
  23. }
  24.  
  25.  
  26. 	//この関数の内側だけを書く
  27.  
  28.  
  29. int main(void) {
  30. 	int n,x,i;
  31. 	int *a;
  32. 	int ans = -1;
  33. 	scanf("%d %d",&n,&x);
  34. 	a = (int*)malloc(sizeof(int)*n);
  35. 	if(a==NULL){
  36. 		printf("ERROR\n");
  37. 		return -1;
  38. 	}
  39. 	for(i=0;i<n;i++){
  40. 		scanf("%d",&a[i]);
  41. 	}
  42. 	ans = binary_search(a,n,x);
  43. 	if(ans != -1) printf("a[%d] = %d\n",ans,a[ans]);
  44. 	else printf("not found\n");
  45. 	free(a);
  46. 	return 0;
  47. }
  48.  
Success #stdin #stdout 0s 5300KB
comments (?)
stdin
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10 7
1 2 3 4 5 6 7 8 9 10
stdout
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a[6] = 7
https://ideone.com/rECFe5
language:
C (gcc 8.3)
created:
10 days ago
visibility:
public

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