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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. int nibuntansaku(int n,int x,int a[]){
  4. 	int lef=0,rig=n-1;
  5. 	int mid;
  6. 	while(lef<=rig){
  7. 		mid=(lef+rig)/2;
  8. 		if(a[mid]<x){
  9. 			lef=mid+1;
  10. 		}else if(a[mid]>x){
  11. 			rig=mid-1;
  12. 		}else if(a[mid]==x){
  13. 			return mid;
  14. 		}
  15. 	}
  16. 	return -1;
  17. }
  18. int main(){
  19. 	int i,n,x;
  20. 	int *a;
  21. 	scanf("%d %d",&n,&x);
  22. 	a=(int *)malloc(sizeof(int)*n);
  23. 	if(a==NULL){
  24. 		printf("ERROR\n");
  25. 		return 0;
  26. 	}
  27. 	for(i=0;i<n;i++){
  28. 		scanf("%d",&a[i]);
  29. 	}
  30. 	int ans=nibuntansaku(n,x,a);
  31. 	if(ans==-1){
  32. 		printf("みつかりませんでした。");
  33. 	}else{
  34. 		printf("a[%d]=%d",ans,x);
  35. 	}
  36. }
Success #stdin #stdout 0s 5328KB
comments (?)
stdin
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5 3
1 2 3 4 5
stdout
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a[2]=3
https://ideone.com/j2RUZs
language:
C (gcc 8.3)
created:
21 hours ago
visibility:
public

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