AlphaBetaSearch.java

// Java program to demonstrate
// working of Alpha-Beta Pruning
import java.io.*;

class GFG {

// Initial values of
// Alpha and Beta
static int MAX = 1000;
static int MIN = -1000;

// Returns optimal value for
// current player (Initially called
// for root and maximizer)
static int minimax(int depth, int nodeIndex,
				Boolean maximizingPlayer,
				int values[], int alpha,
				int beta)
{
	// Terminating condition. i.e
	// leaf node is reached
	if (depth == 3)
		return values[nodeIndex];

	if (maximizingPlayer)
	{
		int best = MIN;

		// Recur for left and
		// right children
		for (int i = 0; i < 2; i++)
		{
			int val = minimax(depth + 1, nodeIndex * 2 + i,
							false, values, alpha, beta);
			best = Math.max(best, val);
			alpha = Math.max(alpha, best);

			// Alpha Beta Pruning
			if (beta <= alpha)
				break;
		}
		return best;
	}
	else
	{
		int best = MAX;

		// Recur for left and
		// right children
		for (int i = 0; i < 2; i++)
		{
			
			int val = minimax(depth + 1, nodeIndex * 2 + i,
							true, values, alpha, beta);
			best = Math.min(best, val);
			beta = Math.min(beta, best);

			// Alpha Beta Pruning
			if (beta <= alpha)
				break;
		}
		return best;
	}
}

	// Driver Code
	public static void main (String[] args)
	{
		
		int values[] = {3, 5, 6, 9, 1, 2, 0, -1};
		System.out.println("The optimal value is : " +
							minimax(0, 0, true, values, MIN, MAX));
	
	}
}