Index Mapping

#include <bits/stdc++.h> 
using namespace std; 
#define MAX 1000 
  
// Since array is global, it is initialized as 0. 
bool has[MAX + 1][2]; 
  
// searching if X is Present in the given array  
// or not. 
bool search(int X) 
{ 
    if (X >= 0) { 
        if (has[X][0] == 1) 
            return true; 
        else
            return false; 
    } 
  
    // if X is negative take the absolute  
    // value of X. 
    X = abs(X); 
    if (has[X][1] == 1) 
        return true; 
  
    return false; 
} 
  
void insert(int a[], int n) 
{ 
    for (int i = 0; i < n; i++) { 
        if (a[i] >= 0)  
            has[a[i]][0] = 1; 
       else
            has[abs(a[i])][1] = 1; 
    } 
} 
  
// Driver code 
int main() 
{ 
    int a[] = { -1, 9, -5, -8, -5, -2 }; 
    int n = sizeof(a)/sizeof(a[0]); 
    insert(a, n); 
    int X = -5; 
    if (search(X) == true) 
       cout << "Present";  
    else
       cout << "Not Present"; 
    return 0; 
}