Tìm Kiếm Nhị Phân

#include<stdio.h>
#include<conio.h>
void sapxep(int arr[], int n){
int a,b,temp;
    for(a = 0; a <n-1;a++){
        for(b = a+1; b<n; b++){
            if(arr[a] > arr[b]){
                temp = arr[a];
                arr[a] = arr[b];
                arr[b] = temp;
            }
        }
    }
        for(b=0;b<n;b++){
        printf("%d\t",arr[b]);
    }
}
int binarySearch(int arr[], int n, int x){
    int mid, left = 0, right = n-1, key=-1;
    while(left <= right){
        mid = (left+right) / 2;
        if(x < arr[mid])
            right = mid - 1;
        else if(x > arr[mid])
            left = mid + 1;
        else{
            key = mid;
            break;
        }
    }
    return key;
}
int main(){
    int n,i, x, k;
    printf("Nhap vao so phan tu: ");scanf("%d",&n);
    int arr[n];
    for(i = 0; i < n; i++){
        printf("a[%d]=",i+1);
        scanf("%d", &arr[i]);
    }
    sapxep(arr, n);
    printf("\nNhap vao gia tri can tim: ");scanf("%d", &x);
    k = binarySearch(arr,n,x);
    if (k >= 0)
        printf("\nGia tri %d tim thay tai vi tri thu %d",x,k+1);
    else printf("\nKhong tim thay %d trong day!",x);
    return 0;
}