2023/10/11

2512. 奖励最顶尖的 K 名学生

算法掌握:

• 自定义排序
• hash表
• 字符分割

解题思路：

通过题意可知，单词不重复，用hash表存储正面和负面的单词

将每个人的句子分割计算

最后对二维表进行排序即可

java code:

class Solution {
    public List<Integer> topStudents(String[] positive_feedback, String[] negative_feedback, String[] report, int[] student_id, int k) {
        List<Integer> res = new ArrayList<>();
        Map<String, Integer> word = new HashMap<>();
        for(String p : positive_feedback) word.put(p, 3);
        for(String n : negative_feedback) word.put(n, -1);

        int[][] score = new int[student_id.length][2];
        for(int i = 0; i < student_id.length; i++){
            String[] temp = report[i].split(" ");
            score[i][0] = student_id[i];
            for(String t : temp){
                if(word.containsKey(t)){
                   score[i][1] += word.get(t);
                }
            }
        }
        Arrays.sort(score, new Comparator<int[]>() {
            @Override
            public int compare(int[] o1, int[] o2) {
                if(o1[1] == o2[1]){
                    return o2[0] - o1[0];
                }
                return o1[1] - o2[1];
            }
        });
        for(int index = score.length - 1; index >= score.length - k; index--){
            res.add(score[index][0]);
        }
        return res;
    }
}

c++ code:

class Solution {
public:
    static bool compare(const vector<int>& o1, const vector<int>& o2) {
        if (o1[1] == o2[1]) {
            return o2[0] < o1[0];
        }
        return o1[1] < o2[1];
    }

    vector<int> topStudents(vector<string>& positive_feedback, vector<string>& negative_feedback, vector<string>& report, vector<int>& student_id, int k) {
        int size = student_id.size();
        vector<int> res;
        unordered_map<string, int> words;
        vector<vector<int>> score(size, vector<int>(2));

        for(string& p : positive_feedback) words[p] = 3;
        for(string& n : negative_feedback) words[n] = -1;

        for(int i = 0; i < size; i++){
            score[i][0] = student_id[i];
            stringstream ss(report[i]);
            string word;
            while (getline(ss, word, ' ')) score[i][1] += words[word];
        }

        sort(score.begin(), score.end(), compare);
        
        for(int i = size - 1; i > size - k - 1; i--) res.push_back(score[i][0]);
        return res;

    }
};