思路其實很簡單，無論再少的步驟，至少要能把矮的堆到平均高度，所以只求 sum(avg - (<avg))即可。

AC代碼：

import java.util.Arrays;
import java.util.Scanner;

/**
 * @author CC11001100
 */
public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		while (sc.hasNextInt()){
			int n = sc.nextInt();
			int[] stacks = new int[n];
			for (int i = 0; i < n; i++) {
				stacks[i] = sc.nextInt();
			}

			System.out.println(resolve(stacks));
		}

	}

	private static int resolve(int[] n) {
		int avg = (int) Arrays.stream(n).average().orElse(0);
		return Arrays.stream(n).map(x -> x >= avg ? 0 : avg - x).sum();
	}

}

題目來源： https://www.nowcoder.com/practice/f1b67248244c4226a5289c993bc28128?tpId=3&tqId=10914&tPage=1&rp=&ru=/ta/hackathon&qru=/ta/hackathon/question-ranking

牛客網編程練習之編程馬拉松：砌墻