Catenyms

Catenyms

时间： 1ms        内存：128M

描述：

A catenym is a pair of words separated by a period such that the last letter of the first word is the same as the last letter of the second. For example, the following are catenyms:

dog.gopher
gopher.rat
rat.tiger
aloha.aloha
arachnid.dog

A compound catenym is a sequence of three or more words separated by periods such that each adjacent pair of words forms a catenym. For example,

aloha.aloha.arachnid.dog.gopher.rat.tiger

Given a dictionary of lower case words, you are to find a compound catenym that contains each of the words exactly once. The first line of standard input contains

t

, the number of test cases. Each test case begins with 3 <=

n

<= 1000 - the number of words in the dictionary.

n

distinct dictionary words follow; each word is a string of between 1 and 20 lowercase letters on a line by itself. For each test case, output a line giving the lexicographically least compound catenym that contains each dictionary word exactly once. Output "***" if there is no solution.

输入：

输出：

示例输入：

2
6
aloha
arachnid
dog
gopher
rat
tiger
3
oak
maple
elm

示例输出：

aloha.arachnid.dog.gopher.rat.tiger
***

提示：

参考答案（内存最优[752]）：

#include <stdio.h>

int i,j,k,m,n;
char buf[1000];

int state;
double base, val;

int v[256];

#define check(x) if (!(x)) {printf("no\n");goto bad;}

#define DSTART 1
#define DEC 2
#define BSTART 3
#define BASE 4
#define BDONE 5

main(){
   for (i=0;i<255;i++) v[i] = -1;
   for (i=0;i<=9;i++) v[i+'0'] = i;
   for (i=0;i<=5;i++) v[i+'a'] = i+10;
   scanf("%d",&n);
   gets(buf);
   while (n--) {
      if (!gets(buf)) {
         printf("Error - short input!\n"); 
         exit(1);
      }
      state = DSTART;
      val = base = 0;
      for (i=0;buf[i];i++) {
         char c = buf[i];
         switch(state) {
            case DSTART: {
               check(v[c] >=0 && v[c] <= 9);
               val = v[c];
               state = DEC;
               break;
            }
            case DEC: {
               if (c == '#') {
                  check(val >= 2 && val <= 16);
                  base = val;
                  val = 0;
                  state = BSTART;
                  break;
               }
               check (v[c] >= 0 && v[c] <= 9);
               val = val * 10 + v[c];
               break;
            }
            case BSTART: {
               check (v[c] >= 0 && v[c] < base);
               val = v[c];
               state = BASE;
               break;
            }
            case BASE: {
               if (c == '#') {
                  state = BDONE;
                  break;
               }
               check (v[c] >= 0 && v[c] < base);
               val = val * base + v[c];
               break;
           }
           case BDONE: {
              check (c == '#');
              check (val >=2 && val <= 16);
              base = val;
              val = 0;
              state = BSTART;
              break;
           }
        }
      }
      check(state == DEC || state == BDONE);
      printf("yes\n");
      bad:;
   }
   if (gets(buf)) printf("Error - excessinput!\n");
}

参考答案（时间最优[0]）：

#include <stdio.h>

int i,j,k,m,n;
char buf[1000];

int state;
double base, val;

int v[256];

#define check(x) if (!(x)) {printf("no\n");goto bad;}

#define DSTART 1
#define DEC 2
#define BSTART 3
#define BASE 4
#define BDONE 5

main(){
   for (i=0;i<255;i++) v[i] = -1;
   for (i=0;i<=9;i++) v[i+'0'] = i;
   for (i=0;i<=5;i++) v[i+'a'] = i+10;
   scanf("%d",&n);
   gets(buf);
   while (n--) {
      if (!gets(buf)) {
         printf("Error - short input!\n"); 
         exit(1);
      }
      state = DSTART;
      val = base = 0;
      for (i=0;buf[i];i++) {
         char c = buf[i];
         switch(state) {
            case DSTART: {
               check(v[c] >=0 && v[c] <= 9);
               val = v[c];
               state = DEC;
               break;
            }
            case DEC: {
               if (c == '#') {
                  check(val >= 2 && val <= 16);
                  base = val;
                  val = 0;
                  state = BSTART;
                  break;
               }
               check (v[c] >= 0 && v[c] <= 9);
               val = val * 10 + v[c];
               break;
            }
            case BSTART: {
               check (v[c] >= 0 && v[c] < base);
               val = v[c];
               state = BASE;
               break;
            }
            case BASE: {
               if (c == '#') {
                  state = BDONE;
                  break;
               }
               check (v[c] >= 0 && v[c] < base);
               val = val * base + v[c];
               break;
           }
           case BDONE: {
              check (c == '#');
              check (val >=2 && val <= 16);
              base = val;
              val = 0;
              state = BSTART;
              break;
           }
        }
      }
      check(state == DEC || state == BDONE);
      printf("yes\n");
      bad:;
   }
   if (gets(buf)) printf("Error - excessinput!\n");
}

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