• Source 
    1. #include<bits/stdc++.h>
    2. #define sz 50005
    3. using namespace std;
    4.  
    5. long long arr[sz];
    6.  
    7. bool found,tag,tag1;
    8.  
    9. int main()
    10. {
    11.     long long n,q,i,j,first,last,middle,m,mid;
    12.  
    13.     while(scanf("%lld",&n)==1)
    14.     {
    15.         for(i=1; i<=n; i++)
    16.         {
    17.             scanf("%lld",arr+i);
    18.         }
    19.  
    20.         scanf("%lld",&q);
    21.  
    22.         for(j=1; j<=q; j++)
    23.         {
    24.  
    25.             scanf("%lld",&m);
    26.  
    27.             found = false;
    28.  
    29.             first = 1;
    30.  
    31.             last = n ;
    32.  
    33.             middle = (first+last)/2;
    34.  
    35.             while( first <= last )
    36.             {
    37.                 if ( arr[middle] < m )
    38.                 {
    39.                     first = middle + 1;
    40.                 }
    41.                 else if(arr[middle]==m)
    42.                 {
    43.                     found = true;
    44.                     break;
    45.                 }
    46.                 else
    47.                 {
    48.                     last = middle - 1;
    49.                 }
    50.  
    51.                 middle = (first + last)/2;
    52.             }
    53.  
    54.             if(found==false)
    55.             {
    56.                 if(middle==0)
    57.                 {
    58.                     printf("X %lld\n",arr[middle+1]);
    59.                 }
    60.                 else if(middle == n)
    61.                 {
    62.                     printf("%lld X\n",arr[middle]);
    63.                 }
    64.                 else
    65.                 {
    66.                     printf("%lld %lld\n",arr[middle],arr[middle+1]);
    67.                 }
    68.             }
    69.             else
    70.             {
    71.                 tag=tag1=false;
    72.  
    73.                 for(i=middle-1;i>=1;i--)
    74.                 {
    75.                     if(arr[i]==m)
    76.                     {
    77.                         continue;
    78.                     }
    79.                     else
    80.                     {
    81.                         tag = 1;
    82.                         printf("%lld",arr[i]);
    83.                         break;
    84.                     }
    85.                 }
    86.                 if(!tag)
    87.                 {
    88.                     printf("X");
    89.                 }
    90.  
    91.                 for(i=middle+1;i<=n;i++)
    92.                 {
    93.                     if(arr[i]==m)
    94.                     {
    95.                         continue;
    96.                     }
    97.                     else
    98.                     {
    99.                         tag1 = 1;
    100.                         printf(" %lld\n",arr[i]);
    101.                         break;
    102.                     }
    103.                 }
    104.                 if(!tag1)
    105.                 {
    106.                     printf(" X\n");
    107.                 }
    108.             }
    109.         }
    110.     }
    111.  
    112.     return 0;
    113. }