浙大PAT 1038题 1038. Recover the Smallest Number

本文提供了一种使用C和Java实现的字符串排序方法,通过自定义比较函数来确保字符串拼接后的最大数值表示。C代码利用了快速排序算法并自定义了一个比较函数cmp;Java版本虽然在大规模数据输入下表现不佳,但也展示了类似的排序逻辑。

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快排飘过,代码如下:

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int cmp(const void *m,const void *n){
  char *a=(char *)m;
  char *b=(char *)n;
  char tmpa[20],tmpb[20];
  strcpy(tmpa,a);
  strcpy(tmpb,b);
  strcat(tmpa,b);
  strcat(tmpb,a);
  return strcmp(tmpa,tmpb);
}
char str[10005][10];
int main(){
  int i,j,n;
  scanf("%d",&n);
  for(i=0;i<n;i++){
    scanf("%s",str[i]);
  }
  qsort(str,n,10*sizeof(char),cmp);
  int flag=0;
  for(i=0;i<n;i++){
    for(j=0;str[i][j]!='\0';j++){
      if(flag==0&&str[i][j]=='0');
      else {flag=1;printf("%c",str[i][j]);}
    }
  }
  if(flag==0) printf("0");//如果所有段都为零,那么必须输出一个零
  printf("\n");
  return 0;
} 


用Java写了一下,那组万级的测试数据超时,用java做pat真是不公平啊。

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		int i,n;
		List<String> strList=new ArrayList<String>();
		Scanner sc=new Scanner(System.in);
		n=sc.nextInt();
		for(i=0;i<n;i++){
			strList.add(sc.next());
		}
		Collections.sort(strList, new MyComparator());
		StringBuilder sb=new StringBuilder();
		for(String str:strList){
			sb.append(str);
		}
		i=0;
		while(i<sb.length()&&sb.charAt(i)=='0'){
			i++;
		}
		if(i==sb.length()){
			System.out.println("0");
		}
		else{
			for(;i<sb.length();i++){
				System.out.print(sb.charAt(i));
			}
			System.out.println();
		}
	}

}
class MyComparator implements Comparator<Object>{
	//返回一个基本类型的整型,返回负数表示o1 小于o2,返回0 表示o1和o2相等,返回正数表示o1大于o2。 
	public int compare(Object o1, Object o2) {
		String s1=(String)o1;
		String s2=(String)o2;
		return (s1+s2).compareTo(s2+s1);
	}	
}


 


 

ECDSA.recover is a function in the ECDSA (Elliptic Curve Digital Signature Algorithm) cryptographic system that allows a user to recover the public key from a given signature and message. This function is useful in situations where the public key is unknown but the signature and message are available. The ECDSA algorithm involves three steps: key generation, signature generation, and signature verification. In the key generation step, a private key is generated using a random number generator, and the corresponding public key is derived from the private key. In the signature generation step, a message is hashed and signed using the private key to generate a signature. In the signature verification step, the signature is verified using the public key to ensure that it was generated by the owner of the private key. In some cases, the public key may not be available, but the signature and message are known. In such cases, the ECDSA.recover function can be used to recover the public key from the signature and message. The function takes three inputs: the message, the signature, and the recovery parameter. The recovery parameter is a number between 0 and 3 that specifies which of the four possible public keys should be recovered from the signature. Once the public key is recovered, it can be used to verify the signature and authenticate the message. Overall, ECDSA.recover is a useful function in the ECDSA cryptographic system that allows for public key recovery in situations where it is unknown but the signature and message are available.
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