fork download
copy 
  1. //第3回 課題１
  2. #include <stdio.h>
  3. #include <stdlib.h>
  4.  
  5. int binary_search(int a[],int n,int x){
  6. int left  = 0;
  7. int right = n - 1;
  8.  
  9. 	while(left <= right){
  10. 		int mid = (left + right) / 2;
  11. 		//printf("%d %d %d :%d\n",lef,mid,rig,a[mid]);
  12.  
  13. 		if(a[mid] == x){
  14. 			return mid;
  15. 		}
  16. 		else if(a[mid] < x){
  17. 			left = mid + 1;
  18. 		}
  19. 		else{
  20. 			right = mid - 1;
  21. 		}
  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 
7 12
1 3 4 9 6 10 12
stdout
copy 
a[6] = 12
https://ideone.com/z3Q2Th
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!