笔试题

https://www.tuhd.top/2017/08/02/2017-08-02-%E6%8B%BC%E5%A4%9A%E5%A4%9A%E7%AC%94%E8%AF%95/

模拟乘法, 大数乘法

import java.util.Scanner;
/**
 * Created by thd on 2017/8/1
 */
public class Main2 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String s1 = sc.next();
        String s2 = sc.next();
        int[] a = new int[s1.length()];
        int[] b = new int[s2.length()];
        int[] c = new int[s1.length() + s2.length()];
        for (int i = 0; i < s1.length(); i++) {
            a[s1.length() - 1- i] = s1.charAt(i) - '0';
        }
        for (int i = 0; i < s2.length(); i++) {
            b[s2.length() - 1 - i] = s2.charAt(i) - '0';
        }
        for (int i = 0; i < s1.length(); i++) {
            for (int j = 0; j < s2.length(); j++) {
                c[i+j]+=a[i]*b[j];
            }
        }
        for (int i = 0; i < c.length - 1; i++) {
            c[i+1]+=c[i]/10;
            c[i]=c[i]%10;
        }
        StringBuffer sb = new StringBuffer();
        boolean flag = true;
        for (int i = c.length - 1; i >= 0; i--) {
            if (c[i] == 0 && flag) {
                continue;
            } else {
                flag = false;
            }
            sb.append(c[i]);
        }
        if (flag) System.out.println(0);
        else
            System.out.println(sb.toString());
    }
}

探险

import java.util.*;
/**
 * Created by thd on 2017/8/1
 */
import java.util.*;
 
public class Main {
     
    static class Node{
        int x;
        int y;
        int key;
        int step;
        public Node(int x,int y,int key,int step){
            this.x=x;
            this.y=y;
            this.key=key;
            this.step=step;
        }
    }
    public static void main(String[] args){
        Scanner in=new Scanner(System.in);
        int N=in.nextInt();
        int M=in.nextInt();
        in.nextLine();
        char[][] G=new char[N][M];
        for(int i=0;i<N;i++){
            G[i]=in.nextLine().toCharArray();
        }
        for(int i=0;i<N;i++){
            for(int j=0;j<M;j++){
                if(G[i][j]=='2'){
                    System.out.println(bfs(i,j,N,M,G));
                    return;
                }
            }
        }
    }
    private static int bfs(int si, int sj,int N,int M,char[][] G) {
        Queue<Node> queue=new LinkedList<>();
        int[][][] mp=new int[101][101][1025];
        int[][] next={{-1,0},{0,-1},{1,0},{0,1}};
         
        queue.offer(new Node(si,sj,0,0));
        while(!queue.isEmpty()){
            Node node=queue.poll();
            for(int i=0;i<4;i++){
                int x=node.x+next[i][0];
                int y=node.y+next[i][1];
                int key=node.key;
                if(x<0||x>=N||y<0||y>=M||G[x][y]=='0') continue;
                // 如果走到了出口 直接return 
                else if(G[x][y]=='3') return node.step+1;
                // 如果走到了有钥匙的位置，捡钥匙
                else if(G[x][y]<='z'&&G[x][y]>='a') key=key|(1<<(G[x][y]-'a'));
                // 如果走到了门的位置,判断是否已经有这个门的钥匙,如果没有就没法走
                else if(G[x][y]<='Z'&&G[x][y]>='A'&&(key&(1<<(G[x][y]-'A')))==0) continue;
                // 将走过的位置标记为1
                if(mp[x][y][key]==0){
                    mp[x][y][key]=1;
                    queue.offer(new Node(x,y,key,node.step+1));
                }
                 
            }
        }
        return -1;
    }
     
}

分巧克力

public class Main3 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] h = new int[n];
        for (int i = 0; i < n; i++) {
            h[i] = sc.nextInt();
        }
        int m = sc.nextInt();
        int[] w = new int[m];
        for (int i = 0; i < m; i++) {
            w[i] = sc.nextInt();
        }
        Arrays.sort(h);
        Arrays.sort(w);
        int res = 0;
        int j = 0;
        for (int i = 0; i < h.length; i++) {
            if (w[j++] >= h[i]) {
                res++;
            }
            else
                i--;
            if (j == w.length) break;
        }
        System.out.println(res);
    }
}

找数组中3个数字的最大乘积

import java.util.Scanner;
/**
 * Created by thd on 2017/8/1
 */
public class Main1 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            int n = scanner.nextInt();
            scanner.nextLine();
            long max1 = 1;
            long max2 = 1;
            long max3 = 1;
            long min1 = 1;
            long min2 = 1;
            for (int i = 0; i < n; i++) {
                long num = scanner.nextLong();
                if (num > 0) {
                    if (num > max1) {
                        max3 = max2;
                        max2 = max1;
                        max1 = num;
                        continue;
                    } else if (num > max2) {
                        max3 = max2;
                        max2 = num;
                    } else if (num > max3) {
                        max3 = num;
                    }
                } else {
                    if (num < min1) {
                        min2 = min1;
                        min1 = num;
                    } else if (num < min2) {
                        min2 = num;
                    }
                }
            }
            if (min1 != 1 || min2 != 1) {
                if (min1 * min2 < max2 * max3) {
                    System.out.println(max2 * max3 * max1);
                } else {
                    System.out.println(min1 * min2 * max1);
                }
            } else {
                System.out.println(max2 * max3 * max1);
            }
        }
    }
}