subject

Given an array of positive numbers arr
The first hand and the second hand can choose to take several values in one position at a time ,
The value should be greater than 0, But less than the rest there
Who gets empty first arr, Who wins . according to arr, Return who wins

The title mean

All the numbers >=0, No one can take every round 0
Who gets the last point first wins

First hand and second hand , extremely clever , Everyone is fully prepared for everything and himself ,
And absolutely rational , Ask you , Give you an array status to return who will win

Conclusion

All the numbers XOR up , If XOR sum is not equal to zero, win first , If XOR and equals 0 The backhand wins

The first big goal :
Let the backhand face all the arrays first 0 The state of .
I don't know how to achieve the big goal , Switch goals ,

An XOR sum in which all numbers are XOR , If I can do it first, I face the XOR of these numbers and it is not equal to zero .
But every time I get it, I let my backhand face the XOR and equals 0, Then the final victory is the first
We know that in the end 0 When XOR and is 0. So play like this , It always has a moment full 0 When , And I can't meet , Will only let the backhand encounter , So my big goal of winning is turned into a seemingly more difficult goal by us .

Example

Write binary , Array 7,5,3 Global XOR and 001

First in 1 Here take one , become 6, Later 5,3 XOR sum 6 Together, XOR and are 0

When the back hand takes it again , No matter which number he takes in which position, he will definitely let XOR and from 0 Become not zero ,
Because he will inevitably change the number of one in a certain position , Changing its XOR and is not 0, Then continue to XOR and change it first 0, The first step is to win .
But what is the premise of doing this ? At the beginning, the XOR and must be non-zero in order to do so , If you face one first, it is XOR and equal 0 The state of , The backhand wins

Code

	public static void printWinner(int[] arr) {
    
		int eor = 0;
		for (int num : arr) {
    
			eor ^= num;
		}
		if (eor == 0) {
    
			System.out.println(" The backhand wins ");
		} else {
    
			System.out.println(" Win first ");
		}
	}