3432. Count Partitions with Even Sum Difference

You are given an integer array nums of length n.

A partition is defined as an index i where 0 <= i < n - 1, splitting the array into two non-empty subarrays such that:

• Left subarray contains indices [0, i].
• Right subarray contains indices [i + 1, n - 1].

Return the number of partitions where the difference between the sum of the left and right subarrays is even.

class Solution {
public:
    int countPartitions(vector<int>& nums) {
        int bit = 0;
        for(auto& n : nums) bit ^= n;
        return bit & 1 ? 0 : nums.size() - 1;
    }
};