第七届蓝桥杯省赛java本科A组试题及解答

1. 煤球数目

2. 生日蜡烛

for(int i=0;i<236;i++){
sum = 0;
for(int j=i;j<236;j++){
System.out.println(sum);
sum += j;
if(sum == 236){
flag = 1;
break;
}
}
if(flag == 1){
System.out.println(i);
break;
}
}
//结果：26

3. 搭积木

public class Main {
static int[] a = new int[10];
static int[] v = new int[10];
static int[][] test = new int[4][4];
static int count = 0;

public void dfs(int x)
{
if(x>9 && judge(a)){
count++;
return;
}

for(int i=0;i<a.length;i++){
if(v[i] == 0){
v[i]=1;
a[x] = i;
dfs(x+1);
v[i] = 0;
}
}

}
public boolean judge(int[] a, int r, int c) {
if (a[0]<a[1]&&a[0]<a[2]&&a[1]<a[3]&&a[1]<a[4]&&a[2]<a[4]&&a[2]<a[5]&&a[3]<a[6]&&a[3]<a[7]&&a[4]<a[7]&&a[4]<a[8]&&a[5]<a[8]&&a[5]<a[9]) {
return true;
}else {
return false;
}

}
public static void main(String[] args) {
Main test = new Main();
test.dfs(0);
System.out.println(count);
}
}

4. 分小组

public class A
{
public static String remain(int[] a)
{
String s = "";
for(int i=0; i<a.length; i++){
if(a[i] == 0) s += (char)(i+'A');
}
return s;
}

public static void f(String s, int[] a)
{
for(int i=0; i<a.length; i++){
if(a[i]==1) continue;

4000
a[i] = 1;
for(int j=i+1; j<a.length; j++){
if(a[j]==1) continue;
a[j]=1;
for(int k=j+1; k<a.length; k++){
if(a[k]==1) continue;
a[k]=1;
System.out.println(s + " "+ (char)('A'+i)  + (char)('A'+j) +  (char)('A'+k)  +  " " + remain(a));  //填空位置
a[k]=0;
}
a[j]=0;
}
a[i] = 0;
}
}

public static void main(String[] args)
{
int[] a = new int[9];
a[0] = 1;

for(int b=1; b<a.length; b++){
a = 1;
for(int c=b+1; c<a.length; c++){
a[c] = 1;
String s = "A" + (char)(b+'A') + (char)(c+'A');
f(s,a);
a[c] = 0;
}
a[b] = 0;
}
}
}

public class A
{
public static void f(int[] a, int k, int n, String s)
{
if(k==a.length){
if(n==0) System.out.println(s);
return;
}

String s2 = s;
for(int i=0; i<=a[k]; i++){
f(a,k+1,n-i,s2);   //填空位置
s2 += (char)(k+'A');
}
}

public static void main(String[] args)
{
int[] a = {4,2,2,1,1,3};

f(a,0,5,"");
}
}

public class Main {
static int[] v = new int[14];// 0 - 13
static int[] a = new int[14];
static int count = 0;
public void dfs(int x){
if(x >13){
count++;
return;
}
for(int i=1;i<14;i++){
if(judge(x-1)){
if(v[i] == 0){
v[i] = 1;
a[x] = i;
dfs(x+1);
v[i] = 0;
}
}else{
continue;
}
}
}
public boolean judge(int x){
if(x == 3 && a[1] + a[2] != a[3]) return false;
else if(x == 6 && a[4] - a[5] != a[6]) return false;
else if(x == 9 && a[7] * a[8] != a[9]) return false;
else if(x == 12 && a[10] != a[11] * a[12]) return false;
else {
return true;
}
}

public static void main(String[] args) {
Main test = new Main();
v[0] = 1;
a[0]=0;
test.dfs(1);
System.out.println(count);

}
}
// 结果: 64

7. 剪邮票

// dfs() 获取5个数， bfs() 判断这5个数是否联通
import java.util.LinkedList;
import java.util.Queue;

public class Main {

public static int num = 0;
public static int[][] next = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
public static int[][] stamp = new int[3][4];
public static int[] visit = new int[12];
public static int[] have = new int[5];

///select five visiable number
public static void dfs(int step,int i){
if(step >= 5){
if(bfs()){
num++;
}
return;
}
for(;i<12;i++){
if(visit[i] == 0){
visit[i] = 1;
have[step] = i;
stamp[i/4][i%4] = 1;
dfs(step+1,i+1);
stamp[i/4][i%4] = 0;
visit[i] = 0;
}
}
}

//    E peek()      ：获取第一个元素，但是不移除；
//    E poll()      ：查询并移除第一个元素；

//    E peekLast()  ：获取最后一个元素，但是不移除；
//    E pop()       ：获取最后一个元素

//    push (e)      : 在链表头部插入一个元素
//    E offer(e)    ：在链表尾部插入一个元素；

// @bfs() -- function is check
public static boolean bfs(){
Queue<Integer> q = new LinkedList<Integer>();
q.offer(have[0]);
stamp[have[0] / 4][have[0] % 4] = -1; // make the first node visit
int step = 1;
int ni,nj;
while(q.peek()!=null){
int e = q.poll();
for(int j=0;j<4;j++){
ni = e / 4 + next[j][0];
nj = e % 4 + next[j][1];
// find the node neighbor , if neighbor node has not visited , then visited
if(ni < 3 && ni >= 0 && nj < 4 && nj >= 0 && stamp[ni][nj] == 1){
stamp[ni][nj] = -1;
step++;
q.offer(ni*4 + nj);
}
}
}
/// clear the information of visiting to stamp
for(int i=0;i<5;i++){
int h = have[i];
stamp[h/4][h%4] = 1;
}
return step == 5;
}

public static void main(String[] args) {
dfs(0, 0);
System.out.println(num);
}
}

8.取球博弈

(0<n1,n2,n3<100)

(0<xi<1000)

import java.util.Scanner;
public class A {
public static int [] n = new int[3];
public static int [] init = new int[5];
public static int [] end = new int[1000];
public static char [] sign = {'-','0','0','+'};
public static void main(String [] args){
Scanner scan = new Scanner(System.in);
for(int i = 0; i < 3; i++){
n[i] = scan.nextInt();
}
int Min = Math.min(n[0], Math.min(n[1], n[2]));
for(int i = 0; i < 5; i++){
init[i] = scan.nextInt();
}
for(int i = 0; i < Min; i++){
end[i] = 2;
}
for(int i = Min; i < end.length; i++){
int temp = 0;
for(int j =0; j < 3; j++){
if(i - n[j] < 0)
continue;
else if(end[i-n[j]] == 3){
if(n[j]%2 != 0)
temp = 1 > temp ? 1 : temp;
}
else if(end[i-n[j]] == 0){
if(n[j]%2 == 0)
temp = 3;
else
temp = 2 > temp ? 2 : temp;
}
else if(end[i-n[j]] == 2){
if(n[j]%2==0)
temp = 2 > temp ? 2 : temp;
else
temp = 3;
}
else if(end[i-n[j]] == 1){
if(n[j]%2==0)
temp = 1 > temp ? 1 : temp;
}
}
end[i] = temp;
}
for(int i = 0; i < 5; i++){
System.out.print(sign[end[init[i]]]+" ");
}
}

}

9. 交换瓶子

import java.util.*;
public class Index{
public static void main(String args[]){
Scanner sc = new Scanner(System.in);
int n,temp;
int count = 0;
n = sc.nextInt();
int[] a = new int
;
for (int i = 0;i<n;i++){
a[i] = sc.nextInt();
}

for(int i = 1;i<a.length-1;i++){
for(int j=i;j<a.length-1;j++){
if(a[i] != i){
temp = a[a[i]];
a[a[i]] = a[i];
a[i] = temp;
count++;
}else{
break;
}
}

}
System.out.println(count);

}
}

10. 压缩变换

import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Index {

public static int n;
public static int[] flag,res;
public static Map<Integer, Integer> map = new HashMap<Integer, Integer>();

public static int cnt(int l,int r){
int sum = 0;
for(int i=l;i<r;i++){
if(flag[i]==1) sum++;
}
return sum;
}

public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner in = new Scanner(System.in);
while(in.hasNext()){
n = in.nextInt();
flag = new int[n+10];
res = new int[n+10];
Arrays.fill(flag, 0);
map.clear();
int t,last=-1;
for(int i=0;i<n;i++){
//nums[i] = in.nextInt();
t = in.nextInt();
if(!map.containsKey(t)){
res[i] = -t;
map.put(t, i);
flag[i] = 1;
}
else{
last = map.get(t);
res[i] = cnt(last+1, i);
flag[last] = 0;
//map.remove(t);
map.put(t, i);
flag[i] = 1;
}
}
for(int i=0;i<n;i++) System.out.print(res[i]+" ");
}
}

}