【PAT】A1038. Recover the Smallest Number(贪心策略、排序)

本文针对PAT A1038题提供了一种有效的解决方案,采用贪心策略和排序方法,确保了组合得到的数字是最小的。特别地,文章详细介绍了如何通过比较两个字符串相加的不同顺序来实现正确的排序逻辑,并分享了作者的AC代码。

【PAT】A1038. Recover the Smallest Number(贪心策略、排序)

@(PAT)

链接:https://www.patest.cn/contests/pat-a-practise/1038

思路:
1. 根据网上得到的资料,贪心策略为:排序,排序条件为a+b< b+a,这样就能保证组合得到的数字最小。这类问题主要是要得到正确的贪心策略。
2. vector最好和string搭配。
3. 输出的时候前面的0要记得去掉。
4. 有一个点是全部为0的情况,记得最后处理。

My AC code:

#define _CRT_SECURE_NO_DEPRECATE

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <map>

#include <cmath>
#include <cstdio>
#include <cstring>
#include <cstdlib>

using namespace std;

bool cmp(string s1, string s2) {
    return s1+s2 < s2+ s1;
}

int main() {
    int n;
    scanf("%d", &n);
    vector<string> vs;
    for (int i = 0; i < n; i++) {
        string temp;
        cin >> temp;
        vs.push_back(temp);
    }
    sort(vs.begin(), vs.end(), cmp);
    bool flag = 0;
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < vs[i].size(); j++) {
            if (flag == 0 && vs[i][j] == '0') {
                continue;
            }
            else {
                flag = 1;
                cout << vs[i][j];
            }
        }
    }
    if (flag == 0) printf("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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