求助vscode神奇代码真的不理解了

#include <iostream>
#define xum xor_sum
#define N 10001000
#define lc (root << 1)
#define rc (lc | 1)
#define mid ((l + r) >> 1)
#define LC l, mid, lc
#define RC mid + 1, r, rc
#define POS int l, int r, int root
#define pos l, r, root
#define INF 999999999
using namespace std;
struct node{
    int xum;
    int max;
    int add;
};
node tr[N*4];
void pushup(int root){
    tr[root].max = max(tr[lc].max,tr[rc].max);
    tr[root].xum = tr[lc].xum ^ tr[rc].xum;
}
int main(){
    return 0;
}