BUPT2012网研院机试Java题解

题目搜集于各位前辈，侵删。

第一题

import java.util.Scanner;public class i1201 {public static void main(String[] args) {// TODO Auto-generated method stubScanner sc = new Scanner(System.in);int T = sc.nextInt();for(int t=0;t<T;t++) {char c = sc.next().charAt(0);String s = sc.next();int sum = 0;for(int i = 0;i<s.length();i++) {if(s.charAt(i)==c) {sum++;}}System.out.println(sum);}sc.close();}}

第二题

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;public class i1202 {static Node root = null;public static void main(String[] args) {// TODO Auto-generated method stubScanner sc = new Scanner(System.in);int T = sc.nextInt();for(int t=0;t<T;t++) {int n = sc.nextInt();int m = sc.nextInt();root = new Node(1,1);for(int i=0;i<n;i++) {int s = sc.nextInt();int f = sc.nextInt();Node father = search(f);Node son = new Node(s,father.depth+1);father.sons.add(son);}int depth = 1;int first = 1;Queue<Node> q = new LinkedList<Node>();q.add(root);while(q.size()!=0) {Node node = q.remove();if(node.depth==depth) {if(first == 1) {System.out.print(node.value);first = 0;}else {System.out.print(" "+node.value);}					}else {depth = node.depth;System.out.println();System.out.print(node.value);first = 0;}for(int i = 0;i<node.sons.size();i++) {q.add(node.sons.get(i));}}}sc.close();}static class Node{int value;ArrayList<Node> sons = new ArrayList<Node>();int depth;public Node(int value, int depth) {super();this.value = value;this.depth = depth;}}static Node search(int value) {Queue<Node> q = new LinkedList<Node>();q.add(root);while(q.size()!=0) {Node n = q.remove();if(n.value == value) {return n;}else {for(int i = 0;i<n.sons.size();i++) {q.add(n.sons.get(i));}}}return null;}}

第三题

import java.util.Scanner;public class i1203 {public static void main(String[] args) {// TODO Auto-generated method stubScanner sc = new Scanner(System.in);int T = sc.nextInt();for(int t=0;t<T;t++) {String s = sc.next();if(ok(s)) {System.out.println("Yes");}else {System.out.println("No");}}sc.close();}static boolean ok(String s) {String[] ss = s.split("\\.");if(ss.length!=4) {return false;}for(int i = 0;i<ss.length;i++) {int a = Integer.parseInt(ss[i]);if(a>=0&&a<=255) {}else {return false;}}return true;}
}

第四题

import java.util.Scanner;
//太懒了没跑代码，思路比较暴力，就是全排列然后依次比较
public class i1204 {static double max = 0;static double maxx = 0;static double maxy = 0;public static void main(String[] args) {// TODO Auto-generated method stubScanner sc = new Scanner(System.in);int T = sc.nextInt();for(int t=0;t<T;t++) {int n = sc.nextInt();Order[] order = new Order[n];for(int i = 0;i<n;i++) {String op = sc.next();int x = sc.nextInt();Order o = new Order(op,x);order[i] = o;}perm(order,0,order.length-1);System.out.println(max);}System.out.println(maxx+"."+maxy);sc.close();}static class Order{String op;int x;public Order(String op, int x) {super();this.op = op;this.x = x;}}static void perm(Order[] order,int a,int b) {if(a==b) {calculate(order);}else {for(int i = a;i<=b;i++) {Order temp = order[a];order[a] = order[i];order[i] = temp;perm(order,a+1,b);temp = order[a];order[a] = order[i];order[i] = temp;}}}static void calculate(Order[] order){double x=0;double y=0;int dir=0;for(int i=0;i<order.length;i++) {Order o = order[i];if(o.op.equals("left")) {dir+=o.x;if(dir>=360) {dir-=360;}}else if(o.op.equals("right")) {dir-=o.x;if(dir<0) {dir+=360;}}else if(o.op.equals("forward")) {double disx = Math.cos(dir)*o.x;double disy = Math.sin(dir)*o.x;x+=disx;y+=disy;}else {double disx = Math.cos(dir)*o.x;double disy = Math.sin(dir)*o.x;x-=disx;y-=disy;}}double dis = Math.sqrt(x*x+y*y);if(dis>max) {max = dis;maxx = x;maxy = y;}}
}