笔画

import java.util.*;public class Main {static Main ybh = new Main();private class StackX {private final int SIZE=1000;private int[] st;private int top;public StackX(){st = new int[SIZE];top = -1;}public void push(int j){st[++top] = j;}public int pop(){return st[top--];}public int peek(){return st[top];}public boolean isEmpty(){return top==-1;}}private class Vertex {public int value;public boolean wasVisited;public Vertex(int a){this.value = a;this.wasVisited = false;}}public static void main(String[] args) {Scanner scan = new Scanner(System.in);int num = scan.nextInt();Vertex vertexList[] = new Vertex[num];int[][]adjArr = new int[num][num];int m = 1;int nVerts = 0;while(num>0){vertexList[nVerts++] = ybh.new Vertex(m);m++;int a = scan.nextInt();int b = scan.nextInt();adjArr[a-1][b-1] = 1;adjArr[b-1][a-1] = 1;num--;}//判断是否是连通图boolean flag = dfs(vertexList,adjArr,nVerts);if(flag){//判断每行1的个数，放进数组，循环数组，若素组元素均是偶数返回true,如果素组中有两个元素是奇数页返回true,否则返回false;int itemCount = 0;List<Integer> ll = new ArrayList<Integer>();for (int i = 0; i < adjArr.length; i++) {for (int j = 0; j < adjArr.length; j++) {if(adjArr[i][j] == 1)itemCount++;}ll.add(itemCount);itemCount = 0;}int []arr = new int[adjArr.length];Iterator<Integer> it = ll.iterator();int index = 0;while (it.hasNext()) {arr[index++] = it.next();}int odd = 0;int even = 0;for (int i = 0; i < arr.length; i++) {if(arr[i]%2==0)even++;elseodd++;}if(even==arr.length || odd==2)System.out.println(true);elseSystem.out.println(false);}else System.out.println(false);}private static boolean dfs(Vertex[] vertexList, int[][] adjArr,int n) {StackX theStack = ybh.new StackX();vertexList[0].wasVisited = true;theStack.push(0);int count = 1;while (!theStack.isEmpty()) {int v = getAdjUnvisiedVertex(vertexList,theStack.peek(),adjArr,n);if(v==-1)theStack.pop();else{vertexList[v].wasVisited = true;theStack.push(v);count++;}}for (int i = 0; i < n; i++) {vertexList[i].wasVisited = false;}if(count == n)return true;elsereturn false;}private static int getAdjUnvisiedVertex(Vertex[] vertexList,int v,int[][] adjArr,int nVerts) {for (int j = 0; j < nVerts; j++) {if(adjArr[v][j]==1 && vertexList[j].wasVisited == false)return j;}return -1;}}