Problem Logic Breakdown

When the number of values is even, the resulting subarrays are as follows:

Test case #1: {1,2,3,4}

1⊕2⊕3⊕4⊕(1⊕2)⊕(2⊕3)⊕(3⊕4)⊕(1⊕2⊕3)⊕(2⊕3⊕4)⊕(1⊕2⊕3⊕4)

• Notice that 1 occurs an even number of times, as does 2, 3, and 4. XORing any number an even number of times produces 0 as a result.

When the number of values is odd, the resulting subarrays are as follows:

1. Test case #2: {1,2,3}

1⊕2⊕3⊕(1⊕2)⊕(2⊕3)⊕(1⊕2⊕3)

• Notice that every even index (0, 2) occurs an odd number of times and that every odd index (1) occurs an even number of times. Recall that XORing a number by itself produces 0 for any even number of XOR operations.

SPOILER

1. If vector<int>'s size() is even, output 0
2. Else XOR the vector for every even index, starting from 0