通过改变大小写来置换字符串
原文:https://www.geeksforgeeks.org/permute-string-changing-case/
打印字符串的所有排列，保持顺序但改变大小写。 例:
Input : ab
Output : AB Ab ab aB
Input : ABC
Output : abc Abc aBc ABc abC AbC aBC ABC
方法 1(天真):天真的方法是遍历整个字符串，对于每个字符，考虑两种情况，(1)改变大小写并重复出现(2)不改变大小写并重复出现。 方法 2(更好)对于长度为 n 的字符串，存在 2 个 n 最大组合。我们可以将其表示为按位运算。 在打印所有子序列中讨论了相同的想法。 以下是上述思路的实现:
C++
// CPP code to print all permutations
// with respect to cases
#include <bits/stdc++.h>
using namespace std;
// Function to generate permutations
void permute(string input)
{
int n = input.length();
// Number of permutations is 2^n
int max = 1 << n;
// Converting string to lower case
transform(input.begin(), input.end(), input.begin(),
::tolower);
// Using all subsequences and permuting them
for (int i = 0; i < max; i++) {
// If j-th bit is set, we convert it to upper case
string combination = input;
for (int j = 0; j < n; j++)
if (((i >> j) & 1) == 1)
combination[j] = toupper(input.at(j));
// Printing current combination
cout << combination << " ";
}
}
// Driver code
int main()
{
permute("ABC");
return 0;
}
Java 语言(一种计算机语言，尤用于创建网站)
// Java program to print all permutations
// with respect to cases
public class PermuteString
{
// Function to generate permutations
static void permute(String input)
{
int n = input.length();
// Number of permutations is 2^n
int max = 1 << n;
// Converting string to lower case
input = input.toLowerCase();
// Using all subsequences and permuting them
for(int i = 0;i < max; i++)
{
char combination[] = input.toCharArray();
// If j-th bit is set, we convert it to upper case
for(int j = 0; j < n; j++)
{
if(((i >> j) & 1) == 1)
combination[j] = (char) (combination[j]-32);
}
// Printing current combination
System.out.print(combination);
System.out.print(" ");
}
}
// Driver Program to test above function
public static void main(String[] args)
{
permute("ABC");
}
}
// This code is contributed by Sumit Ghosh
计算机编程语言
# Python code to print all permutations
# with respect to cases
# Function to generate permutations
def permute(inp):
n = len(inp)
# Number of permutations is 2^n
mx = 1 << n
# Converting string to lower case
inp = inp.lower()
# Using all subsequences and permuting them
for i in range(mx):
# If j-th bit is set, we convert it to upper case
combination = [k for k in inp]
for j in range(n):
if (((i >> j) & 1) == 1):
combination[j] = inp[j].upper()
temp = ""
# Printing current combination
for i in combination:
temp += i
print temp,
# Driver code
permute("ABC")
# This code is contributed by Sachin Bisht
C
// C# program to print all permutations
// with respect to cases
using System;
class PermuteString {
// Function to generate
// permutations
static void permute(String input)
{
int n = input.Length;
// Number of permutations is 2^n
int max = 1 << n;
// Converting string
// to lower case
input = input.ToLower();
// Using all subsequences
// and permuting them
for(int i = 0;i < max; i++)
{
char []combination = input.ToCharArray();
// If j-th bit is set, we
// convert it to upper case
for(int j = 0; j < n; j++)
{
if(((i >> j) & 1) == 1)
combination[j] = (char) (combination[j] - 32);
}
// Printing current combination
Console.Write(combination);
Console.Write(" ");
}
}
// Driver Code
public static void Main()
{
permute("ABC");
}
}
// This code is contributed by Nitin Mittal.
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?php
// PHP program to print all permutations
// with respect to cases
// Function to generate permutations
function permute($input)
{
$n = strlen($input);
// Number of permutations is 2^n
$max = 1 << $n;
// Converting string to lower case
$input = strtolower($input);
// Using all subsequences and permuting them
for($i = 0; $i < $max; $i++)
{
$combination = $input;
// If j-th bit is set, we convert
// it to upper case
for($j = 0; $j < $n; $j++)
{
if((($i >> $j) & 1) == 1)
$combination[$j] = chr(ord($combination[$j]) - 32);
}
// Printing current combination
echo $combination . " ";
}
}
// Driver Code
permute("ABC");
// This code is contributed by mits
?>
java 描述语言
<script>
// javascript program to print all permutations
// with respect to cases
// Function to generate permutations
function permute(input)
{
var n = input.length;
// Number of permutations is 2^n
var max = 1 << n;
// Converting string to lower case
input = input.toLowerCase();
// Using all subsequences and permuting them
for(var i = 0;i < max; i++)
{
var combination = input.split('');
// If j-th bit is set, we convert it to upper case
for(var j = 0; j < n; j++)
{
if(((i >> j) & 1) == 1)
combination[j] = String.fromCharCode(combination[j].charCodeAt(0)-32);
}
// Printing current combination
document.write(combination.join(''));
document.write(" ");
}
}
// Driver Program to test above function
permute("ABC");
// This code contributed by Princi Singh
</script>
输出:
abc Abc aBc ABc abC AbC aBC ABC
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