package main

import (
	"fmt"
)

func subsetXORSum(nums []int) int {
	n := len(nums)
	res := 0
	var depth func(idx int)
	trace := make([]int, 0, 0)
	depth = func(idx int) {
		for i := idx; i < n; i++ {
			trace = append(trace, nums[i])
			res += xorSum(trace)
			depth(i + 1)
			trace = trace[:len(trace)-1]
		}
	}
	depth(0)
	return res
}

func xorSum(nums []int) int {
	res := 0
	for _, v := range nums {
		res ^= v
	}
	return res
}

func main() {
	fmt.Println(subsetXORSum([]int{5,1,6}))
}