810-ChalkboardXORGame.go

package main

// 810. Chalkboard XOR Game
// You are given an array of integers nums represents the numbers written on a chalkboard.

// Alice and Bob take turns erasing exactly one number from the chalkboard, with Alice starting first. 
// If erasing a number causes the bitwise XOR of all the elements of the chalkboard to become 0, then that player loses. 
// The bitwise XOR of one element is that element itself, and the bitwise XOR of no elements is 0.

// Also, if any player starts their turn with the bitwise XOR of all the elements of the chalkboard equal to 0, then that player wins.
// Return true if and only if Alice wins the game, assuming both players play optimally.

// Example 1:
// Input: nums = [1,1,2]
// Output: false
// Explanation: 
// Alice has two choices: erase 1 or erase 2. 
// If she erases 1, the nums array becomes [1, 2]. The bitwise XOR of all the elements of the chalkboard is 1 XOR 2 = 3. Now Bob can remove any element he wants, because Alice will be the one to erase the last element and she will lose. 
// If Alice erases 2 first, now nums become [1, 1]. The bitwise XOR of all the elements of the chalkboard is 1 XOR 1 = 0. Alice will lose.

// Example 2:
// Input: nums = [0,1]
// Output: true

// Example 3:
// Input: nums = [1,2,3]
// Output: true

// Constraints:
//     1 <= nums.length <= 1000
//     0 <= nums[i] < 2^16

import "fmt"

func xorGame(nums []int) bool {
    xor, n := 0, len(nums)
    for i := 0; i < n; i++ {
        xor ^= nums[i]
    }
    if xor == 0 { return true } 
    if n % 2 == 0 { return true }
    return false
}

func main() {
    // Example 1:
    // Input: nums = [1,1,2]
    // Output: false
    // Explanation: 
    // Alice has two choices: erase 1 or erase 2. 
    // If she erases 1, the nums array becomes [1, 2]. The bitwise XOR of all the elements of the chalkboard is 1 XOR 2 = 3. Now Bob can remove any element he wants, because Alice will be the one to erase the last element and she will lose. 
    // If Alice erases 2 first, now nums become [1, 1]. The bitwise XOR of all the elements of the chalkboard is 1 XOR 1 = 0. Alice will lose.
    fmt.Println(xorGame([]int{1,1,2})) // false
    // Example 2:
    // Input: nums = [0,1]
    // Output: true
    fmt.Println(xorGame([]int{0,1})) // true
    // Example 3:
    // Input: nums = [1,2,3]
    // Output: true
    fmt.Println(xorGame([]int{1,2,3})) // true
}