粉刷栅栏问题

java实现：

import java.util.ArrayList;import java.util.Collections;import java.util.Scanner;public class 粉刷栅栏 {private static int sum = 0;public static void main(String[] args) {@SuppressWarnings("resource")Scanner in = new Scanner(System.in);ArrayList<Integer>A = new ArrayList<Integer>();int n ;n = in.nextInt();int element;for (int i = 0; i < n; i++) {element = in.nextInt();A.add(element);}paint(A, 0, n-1);System.out.println(sum);}public static void paint(ArrayList<Integer>A, int left, int right) {if (left > right) {return;}if (left == right) {sum ++;}else {int max = Collections.max(A);int index = A.indexOf(max);if (max > A.size()) {sum ++;paint(A, left, index - 1);paint(A, index + 1, right);} else {ArrayList<Integer> ZeroOf = new ArrayList<Integer>();for (int i = left; i <= right; i++) {int value = A.get(i);value --;A.set(i, value);if (value == 0) {ZeroOf.add(i);}}if (!ZeroOf.isEmpty()) {paint(A, left, ZeroOf.get(0));int j = 1;for (; j < ZeroOf.size(); j++) {paint(A, ZeroOf.get(j-1)+1, ZeroOf.get(j) - 1);}paint(A, ZeroOf.get(j - 1) + 1, right);}}}}}