一

题目描述

 代码

package lan2;import java.util.Scanner;public class demo1 {public static int a;public static int b[]={1,2,3,4,5,6,7,8,9};public static int count=0;public static void main(String[] args) {Scanner in=new Scanner(System.in);a=in.nextInt();dfs(0);System.out.println(count);}public static void dfs(int index){if(index==b.length){if(check(b)){count++;}return;}for(int i=index;i<b.length;i++){swap(b,index,i);dfs(index+1);swap(b,index,i);}}public static void swap(int a[],int i,int j){int temp=a[i];a[i]=a[j];a[j]=temp;}public static boolean check(int b[])//N<1000*1000,所以加号之前最多是6位数{for(int i=0;i<6;i++)//加号之前的数{int jiafa=change(0,i);if(jiafa>=a)continue;for(int j=i+1;j<8;j++)//被除数{int beichushu=change(i+1,j);int chushu=change(j+1,8);if(beichushu%chushu==0 && jiafa+beichushu/chushu==a)return true;}}return false;}public static int change(int i,int j){int sum=0;int a=1;for(int c=j;c>=i;c--){sum+=b[c]*a;a=a*10;}return sum;}
}

 二

题目描述

 代码

package lan2;
public class demo2{public static int count=0;public static void main(String[] args) {digui(5,9,2);System.out.println(count);}public static void digui(int a,int b,int c)//a代表遇到店，b代表遇到花，3代表原来的2斗酒{if(a>0)digui(a-1,b,c*2);if(b>0)digui(a,b-1,c-1);if(a==0 && b==0 && c==1)count++;}
}

 三

题目描述

 代码

package lan2;public class demo3 {public static void main(String[] args) {int a[][]=new int[40][2];a[1][0]=1;a[1][1]=0;a[2][0]=1;a[2][1]=1;for(int i=3;i<40;i++){a[i][0]=a[i-1][1]+a[i-2][1];a[i][1]=a[i-1][0]+a[i-2][0];}System.out.println(a[39][1]);}
}

 四

题目描述

 代码

package lan2;import java.util.Scanner;public class demo4 {public static char a[][];static int n;public static int count=Integer.MAX_VALUE;public static boolean mark[][];public static int[][] direction={{1,0},{0,1},{-1,0},{0,-1}};public static void main(String[] args) {Scanner in=new Scanner(System.in);n=in.nextInt();a=new char[n][n];mark=new boolean[n][n];int x=0,y=0;for(int i=0;i<n;i++){for(int j=0;j<n;j++){a[i][j]=in.next().charAt(0);if(a[i][j]=='A'){x=i;y=j;}}}dfs(x,y,0);System.out.println(count);}public static void dfs(int x,int y,int count1){if(count1>=count)return;if(a[x][y]=='B'){count=count1;return;}mark[x][y]=true;for(int i=0;i<4;i++){int x1=x+direction[i][0];int y1=y+direction[i][1];if(x1<0 || x1>=n || y1<0 || y1>=n)continue;if(a[x1][y1] != a[x][y] && mark[x1][y1]==false)dfs(x1,y1,count1+1);}mark[x][y]=false;}
}

五

题目描述

 代码

package lan2;import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Scanner;
class Node1{int x;int y;int length;String ss;public Node1(int x,int y,int z,String ss){this.x=x;this.y=y;length=z;this.ss=ss;}
}
class demo5{static char[][] arr=new char[30][50];static int[][] mark=new int[30][50];static char[] C={'D','L','R','U'};static LinkedList<Node1> queue=new LinkedList();static int[][] direction={{1,0},{0,-1},{0,1},{-1,0}};static char[] c={'D', 'L', 'R', 'U'};public static void main(String[] args) {Scanner in=new Scanner(System.in);for(int i=0;i<30;i++){String s=in.nextLine();for(int j=0;j<50;j++)arr[i][j]=s.charAt(j);}bfs();System.out.println();}private static void bfs(){Node1 node=new Node1(0,0,0,"");queue.add(node);mark[0][0]=1;while (!queue.isEmpty()){node=queue.poll();if(node.x==29 && node.y==49){ System.out.println(node.length);System.out.println(node.ss);}for(int i=0;i<4;i++){int x1=node.x+direction[i][0];int y1=node.y+direction[i][1];if(x1>=0 && x1<30 && y1>=0 && y1<50 && arr[x1][y1]=='0' && mark[x1][y1]==0){mark[x1][y1]=1;Node1 node1=new Node1(x1,y1,node.length+1,node.ss+c[i]);queue.add(node1);}}}}
}

 六

题目描述

 代码

package lan2;import java.util.LinkedList;
import java.util.Scanner;public class demo6 {public static boolean [][] mark=new boolean[8][8];public static int count=Integer.MAX_VALUE;public static int direction[][]={{1,2},{1,-2},{2,-1},{2,1},{-2,1},{-2,-1},{-1,-2},{-1,2}};public static void main(String[] args) {Scanner in=new Scanner(System.in);int x1=in.nextInt();int y1=in.nextInt();int x2=in.nextInt();int y2=in.nextInt();System.out.println(bfs(x1,y1,x2,y2));}public static int  bfs(int a,int b,int c,int d){if(a==c && b==d)return 0;LinkedList<int[]> queue=new LinkedList<>();queue.add(new int[]{a,b,0});mark[a][b]=true;while (!queue.isEmpty()){int [] p=queue.pollFirst();a=p[0];b=p[1];if(a== c && b==d)break;for(int i=0;i<direction.length;i++){int x=a+direction[i][0];int y=b+direction[i][1];if(x<0 || x>7 || y<0 || y>7)continue;if(mark[x][y])continue;queue.add(new int[]{x,y,p[2]+1});mark[x][y]=true;if(x==c && y==d)count=Math.min(count,p[2]+1);}}return count;}
}

 七

题目描述

 

 代码

package lan2;import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;public class demo7 {private static int []north;private static int []west;private static int [][]mark;private static int n;private static int [][]direction={{0,1},{1,0},{-1,0},{0,-1}};private static List<Integer> list=new ArrayList<>();public static void main(String[] args) {Scanner in= new Scanner(System.in);n=in.nextInt();north=new int[n];west=new int[n];mark=new int[n][n];for(int i=0;i<n;i++)north[i]=in.nextInt();for(int j=0;j<n;j++)west[j]=in.nextInt();mark[0][0]=1;north[0]--;west[0]--;list.add(0);dfs(0,0,0);}private static void dfs(int x,int y,int num){if(x==n-1 && y==n-1){for(int i=0;i<n;i++){if(north[i]!=0 || west[i]!=0)return;}for(int j=0;j<=num;j++){System.out.print(list.get(j)+" ");}return;}for(int k=0;k<4;k++){int x1=x+direction[k][0];int y1=y+direction[k][1];if(x1>=0 && x1<n &&  y1<n && y1>=0 && mark[x1][y1]==0 && west[x1]>0&&north[y1]>0 ){mark[x1][y1]=1;north[y1]--;west[x1]--;list.add(x1*n+y1);dfs(x1,y1,num+1);list.remove(list.size()-1);mark[x1][y1]=0;north[y1]++;west[x1]++;}}}
}

 八

题目描述

 代码

package lan2;import java.util.Scanner;public class demo8 {public static int count=0;public static void main(String[] args) {Scanner in=new Scanner(System.in);int m=in.nextInt();int n=in.nextInt();int o=0;f(m,n,o);System.out.println(count);}public static void f(int m,int n ,int o){if(m<0 || n<0 || o<0)return;if(m==0 && n==0)count++;f(m-1,n,o+1);f(m,n-1,o-1);}
}

九

题目描述

 

 代码

package lan2;import java.util.Scanner;
import java.util.*;
public class demo9{static int[] arr;static int[] visit;static int m;private static int count=0;static int max=0;static int a=0;static List<int[]> []listmap;public static void main(String[] args) {Scanner scanner = new Scanner(System.in);int n=scanner.nextInt();listmap=new ArrayList[n+1];visit=new int[n+1];visit[1]=1;for (int i=1;i<=n;i++){listmap[i]=new ArrayList<>();}for (int i=0;i<n-1;i++){int x=scanner.nextInt();int y=scanner.nextInt();int z=scanner.nextInt();listmap[x].add(new int[]{y,z});listmap[y].add(new int[]{x,z});}// 直观打印邻接表for (int i=1;i<=n;i++){List<int[]> ints = listmap[i];for (int[] arr:ints){System.out.print(arr[0]+" "+ arr[1]+" ");}System.out.println();}dfs(1,0);
//        System.out.println(a);visit=new int[n+1];max=0;visit[a]=1;dfs(a,0);System.out.println((max+10+11)*max/2);}private static void dfs(int point, int dis) {if (dis>max){a=point;max=dis;}for (int i = 0; i <listmap[point].size(); i++) {int y=listmap[point].get(i)[0];if (visit[y]==1) continue;visit[y]=1;dis+=listmap[point].get(i)[1];dfs(y,dis);visit[y]=0;dis-=listmap[point].get(i)[1];}}}

 十

题目描述

 代码

 

package lan2;import java.util.Scanner;public class demo10 {private static int x[][];private static int count=0;private static int n;private static int[] mark;private static int[] mark1;public static void main(String[] args) {Scanner in=new Scanner(System.in);n=in.nextInt();mark=new int[n];mark1=new int[n];x=new int[n][n];for(int i=0;i<n;i++){for(int j=0;j<n;j++)x[i][j]=in.nextInt();}dfs(0);System.out.println(count);}private static void dfs(int index){if(index==n){dfs1(0);return;}for(int i=0;i<n;i++){if(mark[index]!=1 && check(index,i) && x[index][i]!=0){x[index][i]=2;mark[index]=1;dfs(index+1);mark[index]=0;x[index][i]=1;}}}private static void dfs1(int index){if(index==n) {count++;return;}for(int i=0;i<n;i++){if(mark1[index]!=1 && check1(index,i) && x[index][i]==1){x[index][i]=3;mark1[index]=1;dfs1(index+1);mark1[index]=0;x[index][i]=1;}}}private static boolean check(int a,int b){for(int i=a-1;i>=0;i--){if(x[i][b]==2){return false;}if((b-a+i)>=0 && (b-a+i)<n){if(x[i][b-a+i]==2){return false;}}if((a+b-i)>=0 && (a+b-i)<n){if(x[i][a+b-i]==2){return false;}}}return true;}private static boolean check1(int a,int b){for(int i=a-1;i>=0;i--){if(x[i][b]==3){return false;}if((b-a+i)>=0 && (b-a+i)<n){if(x[i][b-a+i]==3){return false;}}if((a+b-i)>=0 && (a+b-i)<n){if(x[i][a+b-i]==3){ return false;}}}return true;}
}