poj1256Anagram（全排列& tolower）

最新推荐文章于 2021-10-21 20:03:01 发布

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本文介绍了一个程序，该程序能够从给定的一组字母中生成所有可能的单词组合，并确保输出的单词按字母顺序排列且不重复。使用了C++中的next_permutation函数来实现这一功能。

tolower

头文件：#include<iostream>
定义函数:int tolower(int c)
函数说明：若参数c为大写字母，则将其对应的小写字母返回
返回值：返回转换后的小写字母，若不须转换则将参数c值返回

poj1256Anagram

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

3
aAb
abc
acba

Sample Output

Aab
Aba
aAb
abA
bAa
baA
abc
acb
bac
bca
cab
cba
aabc
aacb
abac
abca
acab
acba
baac
baca
bcaa
caab
caba
cbaa

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’.

代码：

#include <algorithm>
#include <stdio.h>
#include <iostream>
using namespace std;
bool cmp(char a,char b)
{
    if(tolower(a)==tolower(b))
        return a<b;//如果两个字母转化成小写字母一样，ASCII值小的前面，也就是大写字母在前面
    else return tolower(a)<tolower(b);
}
int main()
{
    int t;
    scanf("%d",&t);
    string s;
    while(t--)
    {
        cin>>s;
        sort(s.begin(),s.end(),cmp);
        do
        {
            cout<<s<<endl;
        }while(next_permutation(s.begin(),s.end(),cmp));
    }
}

next_permutation详解