IndexMapping.java

// Java program to implement direct index 
// mapping with negative values allowed. 
class GFG 
{ 

final static int MAX = 1000; 

// Since array is global, it 
// is initialized as 0. 
static boolean[][] has = new boolean[MAX + 1][2]; 

// searching if X is Present in 
// the given array or not. 
static boolean search(int X) 
{ 
	if (X >= 0) 
	{ 
		if (has[X][0] == true) 
		{ 
			return true; 
		} 
		else
		{ 
			return false; 
		} 
	} 

	// if X is negative take the 
	// absolute value of X. 
	X = Math.abs(X); 
	if (has[X][1] == true) 
	{ 
		return true; 
	} 

	return false; 
} 

static void insert(int a[], int n) 
{ 
	for (int i = 0; i < n; i++) 
	{ 
		if (a[i] >= 0) 
		{ 
			has[a[i]][0] = true; 
		} 
		else
		{ 
			has[Math.abs(a[i])][1] = true; 
		} 
	} 
} 

// Driver code 
public static void main(String args[]) 
{ 
	int a[] = {-1, 9, -5, -8, -5, -2}; 
	int n = a.length; 
	insert(a, n); 
	int X = -5; 
	if (search(X) == true) 
	{ 
		System.out.println("Present"); 
	} 
	else
	{ 
		System.out.println("Not Present"); 
	} 
} 
} 

// This code is contributed vickyjsr