给定一个字符串str ，该字符串包含大写和小写字符。任务是分别对大写和小写字符进行排序，以便如果原始字符串中的第i个位置具有大写字符，则在排序后它不应具有小写字符，反之亦然。
例子：
Input: str = “gEeksfOrgEEkS”
Output: eEfggkEkrEOsS
Input: str = “eDefSR”
Output: eDefRS
方法：采用两个数组lower []和upper []存储给定字符串中所有小写和大写字符的频率，然后再次遍历该字符串，对于遇到的每个小写字符，将其替换为可用的最小小写字符lower []数组，并使用upper []数组替换大写字符。
下面是上述方法的实现：
C++
// C++ implementation of the approach
#include
using namespace std;
#define MAX 26
// Function to return the sorted string
string getSortedString(string s, int n)
{
// To store the frequencies of the
// lowercase and the uppercase
// characters in the given string
int lower[MAX] = { 0 };
int upper[MAX] = { 0 };
for (int i = 0; i < n; i++) {
// If current character is lowercase then
// increment its frequency in
// the lower[] array
if (islower(s[i]))
lower[s[i] - 'a']++;
// Else increment in the upper[] array
else if (isupper(s[i]))
upper[s[i] - 'A']++;
}
// Pointers that point to the smallest lowercase
// and the smallest uppercase characters
// respectively in the given string
int i = 0, j = 0;
while (i < MAX && lower[i] == 0)
i++;
while (j < MAX && upper[j] == 0)
j++;
// For every character in the given string
for (int k = 0; k < n; k++) {
// If the current character is lowercase
// then replace it with the smallest
// lowercase character available
if (islower(s[k])) {
while (lower[i] == 0)
i++;
s[k] = (char)(i + 'a');
// Decrement the frequency
// of the used character
lower[i]--;
}
// Else replace it with the smallest
// uppercase character available
else if (isupper(s[k])) {
while (upper[j] == 0)
j++;
s[k] = (char)(j + 'A');
// Decrement the frequency
// of the used character
upper[j]--;
}
}
// Return the sorted string
return s;
}
// Driver code
int main()
{
string s = "gEeksfOrgEEkS";
int n = s.length();
cout << getSortedString(s, n);
return 0;
} Java
// Java implementation of the approach
import java.lang.Character;
class GFG
{
static int MAX = 26;
public static String getSortedString(StringBuilder s, int n)
{
// To store the frequencies of the
// lowercase and the uppercase
// characters in the given string
int[] lower = new int[MAX];
int[] upper = new int[MAX];
for (int i = 0; i < n; i++)
{
// If current character is lowercase then
// increment its frequency in
// the lower[] array
if (Character.isLowerCase(s.charAt(i)))
lower[s.charAt(i) - 'a']++;
// Else increment in the upper[] array
else if (Character.isUpperCase(s.charAt(i)))
upper[s.charAt(i) - 'A']++;
}
// Pointers that point to the smallest lowercase
// and the smallest uppercase characters
// respectively in the given string
int i = 0, j = 0;
while (i < MAX && lower[i] == 0)
i++;
while (j < MAX && upper[j] == 0)
j++;
// For every character in the given string
for (int k = 0; k < n; k++)
{
// If the current character is lowercase
// then replace it with the smallest
// lowercase character available
if (Character.isLowerCase(s.charAt(k)))
{
while (lower[i] == 0)
i++;
s.setCharAt(k, (char) (i + 'a'));
// Decrement the frequency
// of the used character
lower[i]--;
}
// Else replace it with the smallest
// uppercase character available
else if (Character.isUpperCase(s.charAt(k)))
{
while (upper[j] == 0)
j++;
s.setCharAt(k, (char) (j + 'A'));
// Decrement the frequency
// of the used character
upper[j]--;
}
}
// Return the sorted string
return s.toString();
}
// Driver code
public static void main(String[] args)
{
StringBuilder s = new StringBuilder("gEeksfOrgEEkS");
int n = s.length();
System.out.println(getSortedString(s, n));
}
}
// This code is contributed by
// sanjeev2552Python3
# Python3 implementation of the approach
MAX = 26
# Function to return the sorted string
def getSortedString(s, n) :
# To store the frequencies of the
# lowercase and the uppercase
# characters in the given string
lower = [ 0 ] * MAX;
upper = [ 0 ] * MAX;
for i in range(n) :
# If current character is lowercase then
# increment its frequency in
# the lower[] array
if (s[i].islower()) :
lower[ord(s[i]) - ord('a')] += 1;
# Else increment in the upper[] array
elif (s[i].isupper()) :
upper[ord(s[i]) - ord('A')] += 1;
# Pointers that point to the smallest lowercase
# and the smallest uppercase characters
# respectively in the given string
i = 0; j = 0;
while (i < MAX and lower[i] == 0) :
i += 1;
while (j < MAX and upper[j] == 0) :
j += 1;
# For every character in the given string
for k in range(n) :
# If the current character is lowercase
# then replace it with the smallest
# lowercase character available
if (s[k].islower()) :
while (lower[i] == 0) :
i += 1;
s[k] = chr(i + ord('a'));
# Decrement the frequency
# of the used character
lower[i] -= 1;
# Else replace it with the smallest
# uppercase character available
elif (s[k].isupper()) :
while (upper[j] == 0) :
j += 1;
s[k] = chr(j + ord('A'));
# Decrement the frequency
# of the used character
upper[j] -= 1;
# Return the sorted string
return "".join(s);
# Driver code
if __name__ == "__main__" :
s = "gEeksfOrgEEkS";
n = len(s);
print(getSortedString(list(s), n));
# This code is contributed by AnkitRai01C#
// C# implementation of the approach
using System;
class GFG
{
static int MAX = 26;
// Function to return the sorted string
static string getSortedString(char[] s, int n)
{
// To store the frequencies of the
// lowercase and the uppercase
// characters in the given string
int[] lower = new int[MAX];
int[] upper = new int[MAX];
int i = 0, j = 0;
for (i = 0; i < n; i++)
{
// If current character is lowercase then
// increment its frequency in
// the lower[] array
if (char.IsLower(s[i]))
lower[s[i] - 'a']++;
// Else increment in the upper[] array
else if (char.IsUpper(s[i]))
upper[s[i] - 'A']++;
}
// Pointers that point to the smallest lowercase
// and the smallest uppercase characters
// respectively in the given string
i = 0;
while (i < MAX && lower[i] == 0)
i++;
while (j < MAX && upper[j] == 0)
j++;
// For every character in the given string
for (int k = 0; k < n; k++)
{
// If the current character is lowercase
// then replace it with the smallest
// lowercase character available
if (char.IsLower(s[k]))
{
while (lower[i] == 0)
i++;
s[k] = (char)(i + 'a');
// Decrement the frequency
// of the used character
lower[i]--;
}
// Else replace it with the smallest
// uppercase character available
else if (char.IsUpper(s[k]))
{
while (upper[j] == 0)
j++;
s[k] = (char)(j + 'A');
// Decrement the frequency
// of the used character
upper[j]--;
}
}
// Return the sorted string
return String.Join("", s);
}
// Driver code
public static void Main(String[] args)
{
String s = "gEeksfOrgEEkS";
int n = s.Length;
Console.WriteLine(getSortedString(s.ToCharArray(), n));
}
}
// This code is contributed by 29AjayKumar输出：
eEfggkEkrEOsS
时间复杂度： O(n)
空间复杂度： O(1)