fork download
copy 
  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. 	//この関数の内側だけを書く
  7.   int left = 0;
  8.     int right = n - 1;
  9.  
  10.     int mid;
  11.  
  12.     while(left <= right){
  13.         mid = (left + right) / 2;
  14.  
  15.  
  16.         if(a[mid] == x){
  17.             return mid;
  18.          }else if(a[mid] < x)  {
  19.             left = mid + 1;
  20.      }else{
  21.             right = mid - 1; 
  22.       }
  23.   }
  24.     return -1;
  25. }
  26.  
  27. int main(void) {
  28. 	int n,x,i;
  29. 	int *a;
  30. 	int ans = -1;
  31. 	scanf("%d %d",&n,&x);
  32. 	a = (int*)malloc(sizeof(int)*n);
  33. 	if(a==NULL){
  34. 		printf("ERROR\n");
  35. 		return -1;
  36. 	}
  37. 	for(i=0;i<n;i++){
  38. 		scanf("%d",&a[i]);
  39. 	}
  40. 	ans = binary_search(a,n,x);
  41. 	if(ans != -1) printf("a[%d] = %d\n",ans,a[ans]);
  42. 	else printf("not found\n");
  43. 	free(a);
  44. 	return 0;
  45. }
Success #stdin #stdout 0s 5320KB
comments (?)
stdin
copy 
20 2
1 30 20 55 48 79 72 68
stdout
copy 
not found
https://ideone.com/xEBpTO
language:
C (gcc 8.3)
created:
1 day ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!