PAT 1038. Recover the Smallest Number

本文介绍了C++中处理字符串的一些实用技巧,包括字符串拼接、输入输出方式的选择、字符串排序及转换为字符数组等操作,并提供了一个完整的示例程序。

(1)C++中字符串也可以直接相加

(2)C++字符串用cin输入貌似更好一些

(3)sort也可以对字符串进行排序,而且有默认的比较器

(4)通过const char* ch = out.c_str();可以吧字符串转成字符数组


以后得学C++了,java太容易超时了,。。。。


另外要注意的就是这个题目可以最终结果只有一个0


#include <cstdio>
#include <algorithm>
# include <iostream>
#include <string>

using namespace std;
#define MAX 100001

int cmp (string a, string b) {
    return a + b < b + a;
}

int main()
{
    int N;
    string ss[MAX];

    scanf("%d", &N);
    for(int i=0; i<N; i++)
        cin >> ss[i];

    sort(ss, ss + N, cmp);

    string out;
    for(int i=0; i<N; i++)
       out += ss[i];

    int j = 0;
    const char* ch = out.c_str();
    while(ch[j] == '0')
        j ++;
    
    if(j == out.size())
        printf("0");
    else
        for(; j<out.size(); j++)
            printf("%c", ch[j]);
    
    
    return 0;
}


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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