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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. int arr[2000000];
  4. int n ;
  5. // returns the index at which x is present in the arr
  6. // if not returns -1
  7. int binarySearch(int l, int r , int x){
  8. 	if(l>r)return -1;
  9.  
  10. 	else {
  11. 		int mid =(l+r)/2;
  12. 		if(arr[mid]==x){
  13. 			return mid;
  14. 		}
  15. 		else if(arr[mid]>x){
  16. 			return binarySearch(l,mid-1, x);
  17. 		}
  18. 		else {
  19. 			return binarySearch(mid+1, r, x);
  20. 		}
  21. 	}
  22. }
  23. int main(){
  24. 	// the length of the array
  25.  
  26. 	cin>>n;
  27. 	for(int i=0; i<n; i++){
  28. 		cin>>arr[i];
  29. 	}
  30. 	// if the array was not sorted before
  31. 	sort(arr, arr+n);
  32.  
  33. 	// input the element to be searched
  34. 	int x;
  35. 	cin>>x;
  36.  
  37. 	cout<<"x is present at the index "<<binarySearch(0,n-1, x)<<endl;
  38.  
  39. }
  40.  
Success #stdin #stdout 0s 10960KB
comments (?)
stdin
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8
1 5 6 8 12 24 36 72
24
stdout
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x is present at the index 5
https://ideone.com/ENw8Zm
language:
C++ (gcc 8.3)
created:
10 years ago
visibility:
public

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