POJ 1256 Anagram

Anagram

Time Limit: 1000MS Memory Limit: 10000KTotal Submissions: 12070 Accepted: 4933

Description

You are to write a program that has to generate all possible words from a given set of letters.
Example: Given the word "abc", your program should - by exploring all different combination of the three letters - output the words "abc", "acb", "bac", "bca", "cab" and "cba".
In the word taken from the input file, some letters may appear more than once. For a given word, your program should not produce the same word more than once, and the words should be output in alphabetically ascending order.

Input

The input consists of several words. The first line contains a number giving the number of words to follow. Each following line contains one word. A word consists of uppercase or lowercase letters from A to Z. Uppercase and lowercase letters are to be considered different. The length of each word is less than 13.

Output

For each word in the input, the output should contain all different words that can be generated with the letters of the given word. The words generated from the same input word should be output in alphabetically ascending order. An upper case letter goes before the corresponding lower case letter.

Sample Input

3aAbabcacba

Sample Output

AabAbaaAbabAbAabaAabcacbbacbcacabcbaaabcaacbabacabcaacabacbabaacbacabcaacaabcabacbaa

Hint

An upper case letter goes before the corresponding lower case letter.
So the right order of letters is 'A'<'a'<'B'<'b'<...<'Z'<'z'.

Source

 

 

回溯法

 

#include<stdio.h>

#include<algorithm>

#include<cctype>

using namespace std;

char s[20];

char res[20];

bool b[20];

int N;

int cmp(char a,char b)

{

    if(islower(a)&&islower(b))   return a<b;

    if(isupper(a)&&isupper(b))   return a<b;

    if(islower(a)&&isupper(b))   return a<(b-'A'+'a');

    if(isupper(a)&&islower(b))   return a<=(b-'a'+'A');

}

void backtrace(int n)

{

    if(n==N)

    {

        printf("%s/n",res);

        return ;

    }

    int i;

    for(i=0; i<N; ++i)

    {

        if(b[i]==false)

        {

            res[n]=s[i];

            b[i]=true;

            backtrace(n+1);

            b[i]=false;

            while(i<(N-1) && s[i]==s[i+1])//跳过相同的字符

                i++;

        }

    }

}

int main()

{

    int T;

    while(scanf("%d",&T)!=EOF)

    {

        while(T--)

        {

            scanf("%s",&s);

            N=strlen(s);

            res[N]='/0';

            sort(s,s+N,cmp);

            memset(b,0,sizeof(b));

            backtrace(0);

        }

    }

    return 0;

}

STL:

#include<cstdio>

#include<cstring>

#include<cctype>

#include<algorithm>

using namespace std;

char str[20];

bool cmp(char a,char b)

{

    /*if(islower(a)&&islower(b))   return a<b;

    if(isupper(a)&&isupper(b))   return a<b;

    if(islower(a)&&isupper(b))   return a<(b-'A'+'a');

    if(isupper(a)&&islower(b))   return a<=(b-'a'+'A');*/

    if(tolower(a)==tolower(b))  return a<b;

    return tolower(a)<tolower(b);

}

int main()

{

    int T;

    while(scanf("%d",&T)!=EOF)

    {

        while(T--)

        {

            scanf("%s",str);

            int n=strlen(str);

            sort(str,str+n,cmp);

            printf("%s/n",str);

            while(next_permutation(str,str+n,cmp))//别忘了加CMP

            printf("%s/n",str);

        }

    }

    return 0;

}