package lib;
import java.util.Random;


public class Utils {
	
	private static Random rand = new Random();
	
	/**
	 * Puts the numbers 0 .. v.length - 1 in the array v
	 * in random order.
	 */
	public static int[] createArrayWithElements1TonInRandomOrder(int n) {
		int[] v = new int[n];
		// Create an array with the values 0, 1, 2, ...
		for (int i = 0; i < v.length; i++)
			v[i] = i;
		// Create a random permutation of this vector.
		for (int i = v.length - 1; i > 0; i--) {
			// swap v[i] with a random element v[j], j <= i.
			int j = rand.nextInt(i+1);
			int temp = v[i];
			v[i] = v[j];
			v[j] = temp;
		}
		return v;
	}
	
	public static boolean isPermutaion(int[] arr) {
		int n = arr.length;
		boolean[] found = new boolean[n];
		for(int i: arr){
			if(i<0 || i>=n) return false;
			found[i] = true;
		}
		for(boolean b: found){
			if(!b) return false;
		}
		return true;
	}

	public static String matrixToString(int[][] v) {
		if (v == null)  return "null";
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i < v.length; i++) {
			for (int j = 0; j < v[i].length; j++){
				sb.append(v[i][j]);
				sb.append(" ");
			}
			sb.append("\n");
		}
		return sb.toString();
	}

	public static int indexOf(int arr[], int v){
		for (int i = 0; i < arr.length; i++) {
			if(arr[i] == v) return i;
		}
		return -1;
	}

}