1664. Ways to Make a Fair Array

class Solution {
    
    public int helper(int[] nums) {
        int even = 0;
        int odd = 0;
        int count = 0;
        for(int i = 0; i < nums.length; i++) {
            if((i & 1) == 1) {
                odd += nums[i];
            }
            else {
                even += nums[i];
            }
        }
        for(int i = nums.length - 1; i >= 0; i--) {
            if((i & 1) == 0) {
                even -= nums[i];
                if(i < nums.length - 1) {
                    even += nums[i + 1];
                }
            }
            else {
                odd -= nums[i];
                if(i < nums.length - 1) {
                    odd += nums[i + 1];
                }
            }
            if(odd == even) {
                count++;
            } 
        }
        return count;
    }
    public int waysToMakeFair(int[] nums) {
        return helper(nums);
    }
}