阿里Java笔试题

1. 题目描述

在某射击场有N个靶，每个靶上都有一个分数，存在score数组中。击中第i个靶的得分为score[left] * score[i] * score[right]，同时原left和right两个靶变为相邻的靶。其中得分为0的靶是不能射击的，当left不存在或者不能射击时，得分为 score[i] * score[right]，同理right也遵循此规则;当left和right都不存在或者不能射击时，得分为score[i]。请计算出击中所有能射击的靶，最多能得多少分？

2. 参考题目

312. Burst Balloons 

3. 我的做法

参考leetcode的Discuss进行改写，如有问题，欢迎指教

import java.util.ArrayList;import java.util.List;import java.util.Scanner;public class Main{public static void main(String[] args) {Scanner scanner = new Scanner(System.in);while(scanner.hasNext()){List<Integer>list=new ArrayList<Integer>();int size = scanner.nextInt();for(int i = 0; i< size ; i++)list.add(scanner.nextInt());process(list);}scanner.close();}public static void process(List<Integer> list){List<Integer>tmplist=new ArrayList<Integer>();int sum = 0;int size = list.size();for(int i=0;i<size;i++){if(list.get(i)!=0)tmplist.add(list.get(i));else{int []a=new int[tmplist.size()];for(int j=0;j<tmplist.size();j++){a[j]=tmplist.get(j);}sum+=maxRanks(a);tmplist.clear();}if(i==size-1){int []a=new int[tmplist.size()];for(int j=0;j<tmplist.size();j++){a[j]=tmplist.get(j);}sum+=maxRanks(a);}}System.out.println(sum);}public static int maxRanks(int[] iNums) {int[] nums = new int[iNums.length + 2];int n = 1;for (int x : iNums) if (x > 0) nums[n++] = x;nums[0] = nums[n++] = 1;int[][] memo = new int[n][n];return burst(memo, nums, 0, n - 1);}public static int burst(int[][] memo, int[] nums, int left, int right) {if (left + 1 == right) return 0;if (memo[left][right] > 0) return memo[left][right];int ans = 0;for (int i = left + 1; i < right; ++i)ans = Math.max(ans, nums[left] * nums[i] * nums[right] + burst(memo, nums, left, i) + burst(memo, nums, i, right));memo[left][right] = ans;return ans;}}