牛客题解

文章目录

day4_17
- - **BC149** **简写单词**
  - - - 思路：模拟
      - 代码：
  - dd爱框框
  - - - 思路：滑动窗口（同向双指针）
      - 代码：
  - 除2！
  - - - 思路：模拟+贪心+堆
      - 代码：

day4_17

BC149 简写单词

https://www.nowcoder.com/practice/0cfa856bf0d649b88f6260d878f35bb4?tpId=290&tqId=39937&ru=/exam/oj

思路：模拟

代码：

    public static void main(String[] args) {Scanner in = new Scanner(System.in);while(in.hasNext()){char c = in.next().charAt(0);if(c>='a'&&c<='z'){System.out.print((char)(c-32));}else{System.out.print(c);}}}

dd爱框框

https://ac.nowcoder.com/acm/contest/11211/F

在这里插入图片描述

思路：滑动窗口（同向双指针）

1.从1开始计数的

2.区间内的数字必须严格大于0，因为如果区间中存在小于0的数，left在滑动的时候，可能会增大，会倒逼right回退。只有严格大于0的数，随着left滑动，区间之和才会减小。right就会向后移动。

进窗口：sum += arr[right]
判断条件:sum >=x
更新结果：right-left+1 < retlen retleft = left, retright = right
出窗口：sum-= arr[left]

代码：

import java.util.*;
import java.io.*;
public class Main{public static void main(String[] args )throws IOException{Read in = new Read();int n = in.nextInt(),x = in.nextInt();int[]arr = new int[n+1];for(int i = 1; i<=n ; i++){arr[i] = in.nextInt();}int left = 1,right = 1,sum = 0;int retleft = -1,retright = -1,retlen = n;while(right<=n){//进窗口sum += arr[right];while(sum>=x){//更新结果if(right-left+1 < retlen){retleft = left;retright = right;retlen = right-left+1;}sum -= arr[left++];//出窗口}right++;}System.out.println(retleft+" "+retright);  }
}
class Read{StringTokenizer st = new StringTokenizer("");BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));String next()throws IOException{while(!st.hasMoreTokens()){st = new StringTokenizer(bf.readLine());}return st.nextToken();}String nextLine()throws IOException{return bf.readLine();}int nextInt()throws IOException{return Integer.parseInt(next());}long nextLong()throws IOException{return Long.parseLong(next());}double nextDouble()throws IOException{return Double.parseDouble(next());}
}

除2！

https://ac.nowcoder.com/acm/contest/8563/A

在这里插入图片描述

思路：模拟+贪心+堆

1.优先级队列确保出队的都是最大值

2.如果出队/2之后仍是偶数，再次进队。

代码：

import java.util.*;
import java.util.Scanner;
public class Main{public static void main(String[] args){Scanner in = new Scanner(System.in);int n = in.nextInt();int k = in.nextInt();PriorityQueue<Integer> heap = new PriorityQueue<>((a,b)->{return b-a;});long sum = 0,x;for(int i = 0; i<n; i++){x = in.nextLong();sum += x;if(x%2 == 0){heap.add((int)x);}}while(k-- != 0 && !heap.isEmpty()){long t = heap.poll() / 2;sum -= t;if(t%2 == 0){heap.add((int)t);}}System.out.println(sum);}
}