Method up

src/class201/Code05_OTOCI1.java:36–38

(int x)

	// 汇总点权和
	public static void up(int x) {
		sum[x] = sum[ls[x]] + sum[rs[x]] + arr[x];
	}

	public static boolean isroot(int x) {
		return ls[fa[x]] != x && rs[fa[x]] != x;