暑期实习投到现在大大小小笔试做了好多，基本都只过一题多点，昨天刚刚被xhs虐完，今天做华子的笔试，AK了，头一回AK。算是这段时间找实习处处碰壁唯一能稍微舒缓一下情绪的事情了。希望华子能给机会[牛泪]第一题 数据量不大，狠狠暴力。我这做法并不优。不过数据量小// 4.17 1import java.util.HashMap;import java.util.Scanner;public class Main {    public static void main(String[] args) {        Scanner scan = new Scanner(System.in);        int n = scan.nextInt();        HashMap<String,Integer> m = new HashMap<>();        scan.nextLine();        String s = scan.nextLine();        String str = s;        String t = rem(str);        while(!str.equals(t)){            str = t;            t = rem(t);            if(t.equals("0")) {                str = t;                break;            }        }        System.out.print(str);    }    static String rem(String s){        String[] cards = s.split(" ");        int n = cards.length;        StringBuilder ans = new StringBuilder();        int i = 0;        while(i<n){            String t = cards[i];            int ti = i;            int count = 0;            while(i<n&&t.equals(cards[i])){                count++;                i++;            }            if(count==3){                continue;            }else if(count == 4){                ans.append(t);                ans.append(' ');            }else{                for (int j = ti; j < i; j++) {                    ans.append(t);                    ans.append(' ');                }            }        }        if(ans.length() == 0)return "0";        ans.deleteCharAt(ans.length()-1);        return ans.toString();    }}第二题 建树+bfs写的。因为是字符串，建树挺麻烦的，应该还有更好的方法，例如并查集应该能做。 //4.17 2import java.util.*;public class Main {    static Set<String> fa = new HashSet<>();    static HashMap<String, Set<String>> lm = new HashMap<>();    static HashMap<String, int[]> nm = new HashMap<>();    public static void main(String[] args) {        Scanner scan = new Scanner(System.in);        int M = scan.nextInt();        int N = scan.nextInt();        scan.nextLine();        String[] problems = new String[N];        for (int i = 0; i < N; i++) {            problems[i] = scan.nextLine();        }        for(String line:problems){            String[] items = line.split(" ");            String father = items[1];            String child = items[0];            int lev = Integer.parseInt(items[2]);            int num = Integer.parseInt(items[3]);            if(father.equals("*")){                fa.add(child);                if(!lm.containsKey(child)) lm.put(child,new HashSet<>());                if(!nm.containsKey(child)) nm.put(child,new int[]{0,0});            }else {                if(!lm.containsKey(father))lm.put(father,new HashSet<>());                if(!nm.containsKey(father)) nm.put(father,new int[]{0,0});                if(!lm.containsKey(child))lm.put(child,new HashSet<>());                if(!nm.containsKey(child)) nm.put(child,new int[]{0,0});                lm.get(father).add(child);            }            nm.get(child)[lev]+=num;        }        int ans = 0;        for (String f:fa) {            int x = dfs(f);            if(x>M)ans++;        }        System.out.println(ans);    }    static int dfs(String root){        Set<String> x = lm.get(root);        int[] my = nm.get(root);        int cost = 5*my[0]+2*my[1];        for(String y:x){            cost += dfs(y);        }        return cost;    }}第三题 dijkstra，求完再加个索引一块排序。 不过奇怪的是，给的数据n = 1e4,矩阵都1e8了，java竟然只跑180ms，不知道时间是怎么算的import java.util.*;public class Main {    public static void main(String[] args) {        Scanner scan = new Scanner(System.in);        int n = scan.nextInt();        int[][] g = new int[n][n];        int[] cap = new int[n];        for (int i = 0; i < n; i++) {            for (int j = 0; j < n; j++) {                g[i][j] = scan.nextInt();            }        }        for (int i = 0; i < n; i++) {            cap[i] = scan.nextInt();        }        int s = scan.nextInt();        int ms = scan.nextInt();        int[][] res = dijkstra(g,s);        Arrays.sort(res,(a,b)->a[0]==b[0]?a[1]-b[1]:a[0]-b[0]);        StringBuilder ans = new StringBuilder();        int sum = 0;        for (int i = 1; i < n; i++) {            sum+=cap[res[i][1]];            ans.append(res[i][1]);            ans.append(' ');            if(sum>=ms)break;        }        ans.deleteCharAt(ans.length()-1);        System.out.println(ans);    }    static int[][] dijkstra(int[][]g,int s){        int n = g.length;        int[] dist = new int[n];        Arrays.fill(dist,Integer.MAX_VALUE);        dist[s] = 0;        boolean[] vis = new boolean[n];        for (int i = 0; i < n; i++) {            int t  = -1;            for (int j = 0; j < n; j++) {                if(!vis[j]&&(t==-1||(dist[t]>dist[j]))){                    t = j;                }            }            vis[t] = true;            for (int j = 0; j < n; j++) {                if(g[t][j]<0) continue;                if(dist[t]+g[t][j]<dist[j]){                    dist[j] = dist[t]+g[t][j];                }            }        }        int[][]res = new int[n][2];        for (int i = 0; i < n; i++) {            res[i][0] = dist[i];            res[i][1] = i;        }        return res;    }}