蓝桥日记④2015第六届省赛（软件类）JavaA组➤答案解析
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【蓝桥日记④】2015第六届省赛（软件类）JavaA组➤答案解析
文章目录
1、熊怪吃核桃
解法：暴力模拟
package sixSession;
/*** 2015第六届 1、熊怪吃核桃 ***/
public class test1
public static void main(String[] args)
int n = 1543;
int throwNum = 0;
while (n > 0)
if (n % 2 == 1)
n -= 1;
throwNum += 1;
n /= 2;
System.out.println(throwNum);
答案：
5
2、星系炸弹
解法：时间函数
package sixSession;
import java.text.SimpleDateFormat;
import java.util.Calendar;
/*** 2015第六届 2、星系炸弹 ***/
public class test2
public static void main(String[] args)
Calendar calendar = Calendar.getInstance();
// 注意 month 是从0开始的
calendar.set(2014, 10, 9);
calendar.add(calendar.DATE, 1000);
SimpleDateFormat smdate = new SimpleDateFormat("yyyy-MM-dd");
String sdate = smdate.format(calendar.getTime());
System.out.println(sdate);
答案：
2017-08-05
3、九数分三组
解法：全排列+剪枝
package sixSession;
/*** 2015第六届 3、九数分三组 ***/
public class test3
public static void main(String[] args)
int[] a = 1, 2, 3, 4, 5, 6, 7, 8, 9;
backtrack(a, 0, 9);
private static void backtrack(int[] a, int begin, int end)
if (begin > 6)
int A = a[0] * 100 + a[1] * 10 + a[2];
int B = a[3] * 100 + a[4] * 10 + a[5];
if (2 * A != B) return;
if (begin == end)
helper(a);
return;
for (int i = begin; i < end; i++)
int t = a[begin]; a[begin] = a[i]; a[i] = t;
backtrack(a, begin + 1, end);
t = a[begin]; a[begin] = a[i]; a[i] = t;
private static void helper(int[] a)
int A = a[0] * 100 + a[1] * 10 + a[2];
int B = a[3] * 100 + a[4] * 10 + a[5];
int C = a[6] * 100 + a[7] * 10 + a[8];
if (2 * A != B || 3 * A != C) return;
System.out.print(A + " ");
答案：
192 219 273 327
4、循环节长度
package sixSession;
import java.util.Vector;
/*** 2015第六届 4、循环节长度 ***/
public class test4
public static int f(int n, int m)
n = n % m;
Vector v = new Vector();
for(;;)
v.add(n);
n *= 10;
n = n % m;
if(n==0) return 0;
if(v.indexOf(n)>=0) return v.size() - v.indexOf(n);
public static void main(String[] args)
System.out.println(f(1, 8));
System.out.println(f(8, 3));
System.out.println(f(11, 13));
System.out.println(f(39, 190));
答案：
return v.size() - v.indexOf(n)
5、打印萎形
找规律
package sixSession;
/*** 2015第六届 5、打印萎形 ***/
public class test5
public static void f(int n)
String s = "*";
for (int i = 0; i < 2 * n - 3; i++) s += ".";
s += "*";
String s1 = s + "\\n";
String s2 = "";
for (int i = 0; i < n - 1; i++)
s = "." + s.substring(0, s.length() - 3) + "*";
s1 = s + "\\n" + s1;
s2 += s + "\\n";
System.out.println(s1 + s2);
public static void main(String[] args)
f(7);
答案：
s.substring(0, s.length() - 3)
6、加法变乘法
解法一：排列组合+回溯法
package sixSession;
/*** 2015第六届 6、加法变乘法 ***/
public class test6
public static void main(String[] args)
int[] a = new int[48];
backtrack(a, 0, 48, 2);
private static void backtrack(int[] a, int begin, int end, int k)
if (k == 0)
int pos = check(a);
if (pos != -1 && pos != 10) System.out.println(pos);
return;
for (int i = begin; i < end; i++)
a[i] = 1;
k -= 1;
backtrack(a, i + 1, end, k);
k += 1;
a[i] = 0;
private static int check(int[] a)
int sum = 1, pos = -1;
boolean multi = false;
for (int i = 0; i < 48; i++)
if (a[i] == 0)
sum += i + 2;
multi = false;
else
if (multi == false)
if (pos == -1) pos = i + 1;
sum -= (i + 1);
sum += (i + 1) * (i + 2);
else
return -1;
multi = true;
return sum == 2015 ? pos : -1;
解法二：枚举
package sixSession;
/*** 2015第六届 6、加法变乘法 枚举法 ***/
public class test6_2
public static void main(String[] args)
for (int i = 1; i <= 46; i++)
for (int j = i + 2; j <= 48; j++)
if (i * (i + 1) - (i + i + 1) + j * (j + 1) - (j + j + 1) == 2015 - 1225)
if (i != 10) System.out.println(i);
答案：
16
7、牌型种数
排列组合+递归
package sixSession;
/*** 2015第六届 7、牌型种数 ***/
public class test7
private static int ans;
public static void main(String[] args)
f(0, 0);
System.out.println(ans);
private static void f(int k, int cnt)
if (k > 13 || cnt > 13) return;
if (k == 13 && cnt == 13)
ans++;
return;
for (int i = 0; i < 5; i++)
f(k + 1, cnt + i);
答案：
3598180
8、移动距离
推理坐标
package sixSession;
import java.util.Scanner;
/*** 2015第六届 8、移动距离 ***/
public class test8
public static void main(String[] args)
Scanner sc = new Scanner(System.in);
int w = sc.nextInt();
int m = sc.nextInt();
int n = sc.nextInt();
sc.close();
int rm = m % w == 0 ? m / w : m / w + 1;
int rn = n % w == 0 ? n / w : n / w + 1;
int cm = rm % 2 == 0 ? ((w - m % w + 1) % w) : m % w;
int cn = rn % 2 == 0 ? ((w - n % w + 1) % w) : n % w;
int ans = Math.abs(rm - rn) + Math.abs(cm - cn);
System.out.println(ans);
9、垒骰子
解法一：递归(3/5)，heap超出内存
package sixSession;
import java.util.Scanner;
/*** 2015第六届 9、垒骰子 递归 ***/
public class test9
static final int mod = (int)1e9 + 7;
static final int[] op = 0, 4, 5, 6, 1, 2, 3;
static boolean[][] conflict = new boolean[7][7];
public static void main(String[] args)
Scanner sc = new Scanner(System.in);
int n = sc.nextInt(), m = sc.nextInt();
for (int i = 0; i < m; i++)
int x = sc.nextInt(), y = sc.nextInt();
conflict[x][y] = true;
conflict[y][x] = true;
sc.close();
long ans = 0;
for (int up = 1; up <= 6; up++)
ans = (ans + 4 * f(up, n - 1)) % mod;
System.out.println(ans);
private static long f(int up, int cnt)
if (cnt == 0)
return 1;
long ans = 0;
for (int u = 1; u <= 6; u++)
if (conflict[op[up]][u]) continue;
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