贝壳:月光宝盒的密码(二分查找,暴力破解,动态规划)
作者:互联网
1. 题目描述
图片来源:https://www.nowcoder.com/discuss/220718?type=0&order=0&pos=5&page=1
2. 代码
方法1(动态规划)81%超时
import java.util.Scanner;
public class Main{ private static int N;//序列长度 public static void main(String[] args) { Scanner sc = new Scanner(System.in); N = sc.nextInt(); int [] val = new int[N];//正整数 for (int i = 0; i < N; i++) { val[i] = sc.nextInt(); } int max = 0; int [] dp = new int[N]; for (int i = 0; i < N; i++) { for (int j = 0; j < i; j++) { if(val[j]<val[i]){ dp[i] = Math.max(dp[i],dp[j]+1); max = Math.max(max, dp[i]); } } } System.out.print(max+1); } }
方法二,AC 100
import java.util.Scanner;
public class Main { private static int N;//序列长度 public static void main(String[] args) { Scanner sc = new Scanner(System.in); N = sc.nextInt(); int [] val = new int[N];//正整数 for (int i = 0; i < N; i++) { val[i] = sc.nextInt(); } int max = 0; int [] dp = new int[N]; for(int num: val){ //二分找位置 int j = Arrays.binarySearch(dp, 0,max,num); //找不到新增 j = j<0? -(j+1) : j; dp[j] = num; max = j== max?(++max):max; } System.out.println(max); } }
方法三,自己写二分查找
import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); int n = scanner.nextInt(); int[] number = new int[n]; for (int i = 0; i < n; i++) { number[i] = scanner.nextInt(); } System.out.println(lengthOfLIS(number)); } public static int lengthOfLIS(int[] nums) { int[] top = new int[nums.length]; int piles = 0; for (int i = 0; i < nums.length; i++) { int poker = nums[i]; /***** 搜索左侧边界的二分查找 *****/ int left = 0, right = piles; while (left < right) { int mid = (left + right) / 2; if (top[mid] > poker) { right = mid; } else if (top[mid] < poker) { left = mid + 1; } else { right = mid; } } if (left == piles) piles++; top[left] = poker; } return piles; } }
方法四
import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.util.Arrays; public class Main{ public static void main(String[] args) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); int n = Integer.valueOf(br.readLine().trim()); long[] nums = new long[n]; long[] dp = new long[n]; for(int i = 1; i <= n; i++) { long temp = Long.valueOf(br.readLine().trim()); nums[i] = temp; } for(int i = 0; i < n; i++) { long max = 1; for(int j = 0; j < i; j++) { max = Math.max(max, dp[j]+1); } dp[i] = max; } System.out.println(Arrays.stream(dp).max().orElse(0)); } }
网址:
- https://www.nowcoder.com/discuss/220718?type=0&order=0&pos=5&page=1
- https://www.nowcoder.com/discuss/220715?type=0&order=0&pos=2&page=1
标签:二分,暴力破解,Scanner,int,static,import,new,月光宝盒,public 来源: https://www.cnblogs.com/haimishasha/p/11333148.html