GitHib：https://github.com/FlushHip/AlgorithmnCode/tree/master/%E5%8E%BB%E5%93%AA%E5%84%BF%E7%BD%912018%E6%98%A5%E6%8B%9B%E8%BD%AF%E4%BB%B6%E5%BC%80%E5%8F%91%E5%B7%A5%E7%A8%8B%E5%B8%88%E7%BC%96%E7%A8%8B%E9%A2%98

全部AC，

1.

BFS

#include <bits/stdc++.h>

using namespace std;

int main()
{
    string src, des;
    cin >> src;
    des = src;
    reverse(des.begin(), des.end());
    vector<string> arr;
    for (string str; cin >> str; arr.push_back(str)) {}
    arr.push_back(des);
    queue<pair<string, int> > que;
    que.emplace(src, 1);
    bool isOk = false;
    while (!que.empty()) {
        auto now = que.front();
        que.pop();

        if (now.first == des) {
            cout << now.second << endl;
            isOk = true;
            break;
        }

            if (now.second > 99)
            continue;
        for (auto it = arr.begin(); it != arr.end(); ++it) {
            int sum = 0;
            for (int i = 0; i < (int)now.first.size(); i++)
                sum += now.first[i] != (*it)[i];
            if (sum == 1)
                que.emplace(*it, now.second + 1);
        }
    }
    if (!isOk)
        puts("0");
    return 0;
}

2.

二进制枚举集合

import java.util.*;

public class Main {

    public Scanner cin = new Scanner(System.in);

    Main() {
        while (cin.hasNext()) {
            int n = cin.nextInt(), m = cin.nextInt();
            boolean isOk = false;
            ArrayList<Integer> arr = new ArrayList<Integer>();
            for (int i = 0, x; i < n; i++)
                if ((x = cin.nextInt()) <= m)
                    arr.add(x);
            for (int i = 0; i < (1 << arr.size()); i++) {
                int sum = 0;
                for (int bit = 0; bit < arr.size(); bit++)
                    if ((i & (1 << bit)) != 0)
                        sum += arr.get(bit);
                if (sum == m) {
                    isOk = true;
                    break;
                }
            }
            System.out.println(isOk ? "perfect" : "good");
        }
    }

    public static void main(String[] args) {
        new Main();
    }
}