How to Reverse Only Letters and Vowels in a String Using C++
Asked 8 months ago
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All the characters that are not English letters remain in the same position.
All the English letters (lowercase or uppercase) should be reversed.
Return s after reversing it.
for example = d o g -g o d @ 4 3
actual reverse = 3 4 @ d o g - g o d
according to rule = 3 4 d - o g g @ o d
Approch Two Pointer Approch
d o g - g o d @ 4 3
/ /
low high
if low and high both are alphabets , then swap
if s[high] is not alphabet high --
if s[low] is not alphabet low ++
Okay !
how can we justify wheather a char is Alphabert
a-z --> [97-122] ascii values
A-Z -> [65-90] ascii valies
if ((ch>=97 && ch<=122) || (ch>= 65 && ch<=90))
{
true ! its Alphabet
}
Alternative is using inbuild function : isalpha()
using namespace std;
#include <iostream>
#include <algorithm>
#include <vector>
string reverseOnlyLetters(string s)
{
int low = 0;
int high = s.size() - 1;
while (low < high)
{
if (isalpha(s[low]) && isalpha(s[high]))
{
swap(s[low], s[high]);
low++, high--;
}
else if (!isalpha(s[low]))
{
low++;
}
else
{
high--;
}
}
return s;
};
int main()
{
string s;
cout << "Enter the String : " << endl;
cin >> s;
cout << "The Reverse Pattren is : " << reverseOnlyLetters(s) << endl;
return 0;
}
Revesing only Vowels in a String
// similar Problem ! reverse only letters
// vowels = A E I O U // a e i o u
// example Devloom
// Dovloem
using namespace std;
#include <iostream>
#include <algorithm>
#include <vector>
bool isVowel(char ch)
{
ch = tolower(ch);
return ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u';
}
string reverseVowels(string s)
{
int low = 0;
int high = s.size() - 1;
while (low < high)
{
if (isVowel(s[low]) && isVowel(s[high]))
{
swap(s[low], s[high]);
low++, high--;
}
else if (!isVowel(s[low]))
{
low++;
}
else
{
high--;
}
}
return s;
};
int main()
{
string s;
cout << "Enter the String : " << endl;
cin >> s;
cout << "The Reverse Vowels of a String is : " << reverseVowels(s) << endl;
return 0;
}Share