//#solution 1 sum[level % 2 == 0 ? 0 : 1] += root.val; //#solution 2 int a = (level % 2 == 0) ? (sum[0] += root.val) : (sum[1] += root.val); //#solution 3 if(level % 2 == 0) { sum[0] += root.val; } else { sum[1] += root.val; }